diff --git a/cmd_connection.go b/cmd_connection.go
index 521f3d9..e403c94 100644
--- a/cmd_connection.go
+++ b/cmd_connection.go
@@ -192,15 +192,7 @@ func (m *Miniredis) cmdHello(c *server.Peer, cmd string, args []string) {
 
 // ECHO
 func (m *Miniredis) cmdEcho(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
diff --git a/cmd_geo.go b/cmd_geo.go
index 97f74c3..4d35a75 100644
--- a/cmd_geo.go
+++ b/cmd_geo.go
@@ -24,17 +24,16 @@ func commandsGeo(m *Miniredis) {
 
 // GEOADD
 func (m *Miniredis) cmdGeoadd(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 || len(args[1:])%3 != 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+
+	if len(args[1:])%3 != 0 {
+		setDirty(c)
+		c.WriteError(errWrongNumber(cmd))
 		return
 	}
+
 	key, args := args[0], args[1:]
 
 	withTx(m, c, func(c *server.Peer, ctx *connCtx) {
@@ -83,15 +82,7 @@ func (m *Miniredis) cmdGeoadd(c *server.Peer, cmd string, args []string) {
 
 // GEODIST
 func (m *Miniredis) cmdGeodist(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -141,17 +132,10 @@ func (m *Miniredis) cmdGeodist(c *server.Peer, cmd string, args []string) {
 
 // GEOPOS
 func (m *Miniredis) cmdGeopos(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
+
 	key, args := args[0], args[1:]
 
 	withTx(m, c, func(c *server.Peer, ctx *connCtx) {
@@ -187,15 +171,7 @@ type geoDistance struct {
 
 // GEORADIUS and GEORADIUS_RO
 func (m *Miniredis) cmdGeoradius(c *server.Peer, cmd string, args []string) {
-	if len(args) < 5 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(5)) {
 		return
 	}
 
@@ -374,15 +350,7 @@ func (m *Miniredis) cmdGeoradius(c *server.Peer, cmd string, args []string) {
 
 // GEORADIUSBYMEMBER and GEORADIUSBYMEMBER_RO
 func (m *Miniredis) cmdGeoradiusbymember(c *server.Peer, cmd string, args []string) {
-	if len(args) < 4 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(4)) {
 		return
 	}
 
diff --git a/cmd_hash.go b/cmd_hash.go
index 5533295..0c30e2a 100644
--- a/cmd_hash.go
+++ b/cmd_hash.go
@@ -32,15 +32,7 @@ func commandsHash(m *Miniredis) {
 
 // HSET
 func (m *Miniredis) cmdHset(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -66,15 +58,7 @@ func (m *Miniredis) cmdHset(c *server.Peer, cmd string, args []string) {
 
 // HSETNX
 func (m *Miniredis) cmdHsetnx(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -113,15 +97,7 @@ func (m *Miniredis) cmdHsetnx(c *server.Peer, cmd string, args []string) {
 
 // HMSET
 func (m *Miniredis) cmdHmset(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -151,15 +127,7 @@ func (m *Miniredis) cmdHmset(c *server.Peer, cmd string, args []string) {
 
 // HGET
 func (m *Miniredis) cmdHget(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -188,15 +156,7 @@ func (m *Miniredis) cmdHget(c *server.Peer, cmd string, args []string) {
 
 // HDEL
 func (m *Miniredis) cmdHdel(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -242,15 +202,7 @@ func (m *Miniredis) cmdHdel(c *server.Peer, cmd string, args []string) {
 
 // HEXISTS
 func (m *Miniredis) cmdHexists(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -285,15 +237,7 @@ func (m *Miniredis) cmdHexists(c *server.Peer, cmd string, args []string) {
 
 // HGETALL
 func (m *Miniredis) cmdHgetall(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -322,15 +266,7 @@ func (m *Miniredis) cmdHgetall(c *server.Peer, cmd string, args []string) {
 
 // HKEYS
 func (m *Miniredis) cmdHkeys(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -358,15 +294,7 @@ func (m *Miniredis) cmdHkeys(c *server.Peer, cmd string, args []string) {
 
 // HSTRLEN
 func (m *Miniredis) cmdHstrlen(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -392,15 +320,7 @@ func (m *Miniredis) cmdHstrlen(c *server.Peer, cmd string, args []string) {
 
 // HVALS
 func (m *Miniredis) cmdHvals(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -429,15 +349,7 @@ func (m *Miniredis) cmdHvals(c *server.Peer, cmd string, args []string) {
 
 // HLEN
 func (m *Miniredis) cmdHlen(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -462,15 +374,7 @@ func (m *Miniredis) cmdHlen(c *server.Peer, cmd string, args []string) {
 
 // HMGET
 func (m *Miniredis) cmdHmget(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -503,15 +407,7 @@ func (m *Miniredis) cmdHmget(c *server.Peer, cmd string, args []string) {
 
 // HINCRBY
 func (m *Miniredis) cmdHincrby(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -546,15 +442,7 @@ func (m *Miniredis) cmdHincrby(c *server.Peer, cmd string, args []string) {
 
 // HINCRBYFLOAT
 func (m *Miniredis) cmdHincrbyfloat(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -593,15 +481,7 @@ func (m *Miniredis) cmdHincrbyfloat(c *server.Peer, cmd string, args []string) {
 
 // HSCAN
 func (m *Miniredis) cmdHscan(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -685,15 +565,7 @@ func (m *Miniredis) cmdHscan(c *server.Peer, cmd string, args []string) {
 
 // HRANDFIELD
 func (m *Miniredis) cmdHrandfield(c *server.Peer, cmd string, args []string) {
-	if len(args) > 3 || len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, between(1, 3)) {
 		return
 	}
 
diff --git a/cmd_hll.go b/cmd_hll.go
index ffb4d6f..c7963fa 100644
--- a/cmd_hll.go
+++ b/cmd_hll.go
@@ -11,15 +11,7 @@ func commandsHll(m *Miniredis) {
 
 // PFADD
 func (m *Miniredis) cmdPfadd(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -40,15 +32,7 @@ func (m *Miniredis) cmdPfadd(c *server.Peer, cmd string, args []string) {
 
 // PFCOUNT
 func (m *Miniredis) cmdPfcount(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -69,15 +53,7 @@ func (m *Miniredis) cmdPfcount(c *server.Peer, cmd string, args []string) {
 
 // PFMERGE
 func (m *Miniredis) cmdPfmerge(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
diff --git a/cmd_list.go b/cmd_list.go
index 5819945..c4f397c 100644
--- a/cmd_list.go
+++ b/cmd_list.go
@@ -52,15 +52,7 @@ func (m *Miniredis) cmdBrpop(c *server.Peer, cmd string, args []string) {
 }
 
 func (m *Miniredis) cmdBXpop(c *server.Peer, cmd string, args []string, lr leftright) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -115,15 +107,7 @@ func (m *Miniredis) cmdBXpop(c *server.Peer, cmd string, args []string, lr leftr
 
 // LINDEX
 func (m *Miniredis) cmdLindex(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -164,16 +148,7 @@ func (m *Miniredis) cmdLindex(c *server.Peer, cmd string, args []string) {
 
 // LPOS key element [RANK rank] [COUNT num-matches] [MAXLEN len]
 func (m *Miniredis) cmdLpos(c *server.Peer, cmd string, args []string) {
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
-		return
-	}
-
-	if len(args) == 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -311,15 +286,7 @@ func (m *Miniredis) cmdLpos(c *server.Peer, cmd string, args []string) {
 
 // LINSERT
 func (m *Miniredis) cmdLinsert(c *server.Peer, cmd string, args []string) {
-	if len(args) != 4 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(4)) {
 		return
 	}
 
@@ -378,15 +345,7 @@ func (m *Miniredis) cmdLinsert(c *server.Peer, cmd string, args []string) {
 
 // LLEN
 func (m *Miniredis) cmdLlen(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -421,15 +380,7 @@ func (m *Miniredis) cmdRpop(c *server.Peer, cmd string, args []string) {
 }
 
 func (m *Miniredis) cmdXpop(c *server.Peer, cmd string, args []string, lr leftright) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -513,15 +464,7 @@ func (m *Miniredis) cmdRpush(c *server.Peer, cmd string, args []string) {
 }
 
 func (m *Miniredis) cmdXpush(c *server.Peer, cmd string, args []string, lr leftright) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -559,15 +502,7 @@ func (m *Miniredis) cmdRpushx(c *server.Peer, cmd string, args []string) {
 }
 
 func (m *Miniredis) cmdXpushx(c *server.Peer, cmd string, args []string, lr leftright) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -600,15 +535,7 @@ func (m *Miniredis) cmdXpushx(c *server.Peer, cmd string, args []string, lr left
 
 // LRANGE
 func (m *Miniredis) cmdLrange(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -650,15 +577,7 @@ func (m *Miniredis) cmdLrange(c *server.Peer, cmd string, args []string) {
 
 // LREM
 func (m *Miniredis) cmdLrem(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -724,15 +643,7 @@ func (m *Miniredis) cmdLrem(c *server.Peer, cmd string, args []string) {
 
 // LSET
 func (m *Miniredis) cmdLset(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -777,15 +688,7 @@ func (m *Miniredis) cmdLset(c *server.Peer, cmd string, args []string) {
 
 // LTRIM
 func (m *Miniredis) cmdLtrim(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -831,15 +734,7 @@ func (m *Miniredis) cmdLtrim(c *server.Peer, cmd string, args []string) {
 
 // RPOPLPUSH
 func (m *Miniredis) cmdRpoplpush(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -864,15 +759,7 @@ func (m *Miniredis) cmdRpoplpush(c *server.Peer, cmd string, args []string) {
 
 // BRPOPLPUSH
 func (m *Miniredis) cmdBrpoplpush(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -918,15 +805,7 @@ func (m *Miniredis) cmdBrpoplpush(c *server.Peer, cmd string, args []string) {
 
 // LMOVE
 func (m *Miniredis) cmdLmove(c *server.Peer, cmd string, args []string) {
-	if len(args) != 4 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(4)) {
 		return
 	}
 
@@ -979,15 +858,7 @@ func (m *Miniredis) cmdLmove(c *server.Peer, cmd string, args []string) {
 
 // BLMOVE
 func (m *Miniredis) cmdBlmove(c *server.Peer, cmd string, args []string) {
-	if len(args) != 5 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(5)) {
 		return
 	}
 
diff --git a/cmd_object.go b/cmd_object.go
index b958a95..e8117c5 100644
--- a/cmd_object.go
+++ b/cmd_object.go
@@ -14,15 +14,7 @@ func commandsObject(m *Miniredis) {
 
 // OBJECT
 func (m *Miniredis) cmdObject(c *server.Peer, cmd string, args []string) {
-	if len(args) == 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
diff --git a/cmd_pubsub.go b/cmd_pubsub.go
index 0fc9f0d..571431e 100644
--- a/cmd_pubsub.go
+++ b/cmd_pubsub.go
@@ -173,15 +173,7 @@ func (m *Miniredis) cmdPunsubscribe(c *server.Peer, cmd string, args []string) {
 
 // PUBLISH
 func (m *Miniredis) cmdPublish(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
diff --git a/cmd_scripting.go b/cmd_scripting.go
index 188a15e..340ccc4 100644
--- a/cmd_scripting.go
+++ b/cmd_scripting.go
@@ -151,17 +151,10 @@ func compile(script string) (*lua.FunctionProto, error) {
 }
 
 func (m *Miniredis) cmdEval(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
+
 	ctx := getCtx(c)
 	if ctx.nested {
 		c.WriteError(msgNotFromScripts(ctx.nestedSHA))
@@ -180,17 +173,10 @@ func (m *Miniredis) cmdEval(c *server.Peer, cmd string, args []string) {
 }
 
 func (m *Miniredis) cmdEvalsha(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
+
 	ctx := getCtx(c)
 	if ctx.nested {
 		c.WriteError(msgNotFromScripts(ctx.nestedSHA))
@@ -211,15 +197,7 @@ func (m *Miniredis) cmdEvalsha(c *server.Peer, cmd string, args []string) {
 }
 
 func (m *Miniredis) cmdScript(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
diff --git a/cmd_server.go b/cmd_server.go
index 5fe55dd..cd74704 100644
--- a/cmd_server.go
+++ b/cmd_server.go
@@ -23,15 +23,7 @@ func commandsServer(m *Miniredis) {
 
 // MEMORY
 func (m *Miniredis) cmdMemory(c *server.Peer, cmd string, args []string) {
-	if len(args) == 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -85,15 +77,7 @@ func (m *Miniredis) cmdMemory(c *server.Peer, cmd string, args []string) {
 
 // DBSIZE
 func (m *Miniredis) cmdDbsize(c *server.Peer, cmd string, args []string) {
-	if len(args) > 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(0)) {
 		return
 	}
 
@@ -152,15 +136,7 @@ func (m *Miniredis) cmdFlushdb(c *server.Peer, cmd string, args []string) {
 
 // TIME
 func (m *Miniredis) cmdTime(c *server.Peer, cmd string, args []string) {
-	if len(args) > 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(0)) {
 		return
 	}
 
diff --git a/cmd_set.go b/cmd_set.go
index 12e4d58..7d01bb2 100644
--- a/cmd_set.go
+++ b/cmd_set.go
@@ -33,15 +33,7 @@ func commandsSet(m *Miniredis) {
 
 // SADD
 func (m *Miniredis) cmdSadd(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -62,15 +54,7 @@ func (m *Miniredis) cmdSadd(c *server.Peer, cmd string, args []string) {
 
 // SCARD
 func (m *Miniredis) cmdScard(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -96,15 +80,7 @@ func (m *Miniredis) cmdScard(c *server.Peer, cmd string, args []string) {
 
 // SDIFF
 func (m *Miniredis) cmdSdiff(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -128,15 +104,7 @@ func (m *Miniredis) cmdSdiff(c *server.Peer, cmd string, args []string) {
 
 // SDIFFSTORE
 func (m *Miniredis) cmdSdiffstore(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -159,15 +127,7 @@ func (m *Miniredis) cmdSdiffstore(c *server.Peer, cmd string, args []string) {
 
 // SINTER
 func (m *Miniredis) cmdSinter(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -191,15 +151,7 @@ func (m *Miniredis) cmdSinter(c *server.Peer, cmd string, args []string) {
 
 // SINTERSTORE
 func (m *Miniredis) cmdSinterstore(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -222,15 +174,7 @@ func (m *Miniredis) cmdSinterstore(c *server.Peer, cmd string, args []string) {
 
 // SINTERCARD
 func (m *Miniredis) cmdSintercard(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -293,15 +237,7 @@ func (m *Miniredis) cmdSintercard(c *server.Peer, cmd string, args []string) {
 
 // SISMEMBER
 func (m *Miniredis) cmdSismember(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -330,15 +266,7 @@ func (m *Miniredis) cmdSismember(c *server.Peer, cmd string, args []string) {
 
 // SMEMBERS
 func (m *Miniredis) cmdSmembers(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -368,15 +296,7 @@ func (m *Miniredis) cmdSmembers(c *server.Peer, cmd string, args []string) {
 
 // SMISMEMBER
 func (m *Miniredis) cmdSmismember(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -412,15 +332,7 @@ func (m *Miniredis) cmdSmismember(c *server.Peer, cmd string, args []string) {
 
 // SMOVE
 func (m *Miniredis) cmdSmove(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -456,15 +368,7 @@ func (m *Miniredis) cmdSmove(c *server.Peer, cmd string, args []string) {
 
 // SPOP
 func (m *Miniredis) cmdSpop(c *server.Peer, cmd string, args []string) {
-	if len(args) == 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -547,22 +451,15 @@ func (m *Miniredis) cmdSpop(c *server.Peer, cmd string, args []string) {
 
 // SRANDMEMBER
 func (m *Miniredis) cmdSrandmember(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
+
 	if len(args) > 2 {
 		setDirty(c)
 		c.WriteError(msgSyntaxError)
 		return
 	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
-		return
-	}
 
 	key := args[0]
 	count := 0
@@ -625,15 +522,7 @@ func (m *Miniredis) cmdSrandmember(c *server.Peer, cmd string, args []string) {
 
 // SREM
 func (m *Miniredis) cmdSrem(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -658,15 +547,7 @@ func (m *Miniredis) cmdSrem(c *server.Peer, cmd string, args []string) {
 
 // SUNION
 func (m *Miniredis) cmdSunion(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -690,15 +571,7 @@ func (m *Miniredis) cmdSunion(c *server.Peer, cmd string, args []string) {
 
 // SUNIONSTORE
 func (m *Miniredis) cmdSunionstore(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -721,15 +594,7 @@ func (m *Miniredis) cmdSunionstore(c *server.Peer, cmd string, args []string) {
 
 // SSCAN
 func (m *Miniredis) cmdSscan(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
diff --git a/cmd_sorted_set.go b/cmd_sorted_set.go
index 85bc569..9838e39 100644
--- a/cmd_sorted_set.go
+++ b/cmd_sorted_set.go
@@ -46,15 +46,7 @@ func commandsSortedSet(m *Miniredis) {
 
 // ZADD
 func (m *Miniredis) cmdZadd(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -194,15 +186,7 @@ outer:
 
 // ZCARD
 func (m *Miniredis) cmdZcard(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -227,15 +211,7 @@ func (m *Miniredis) cmdZcard(c *server.Peer, cmd string, args []string) {
 
 // ZCOUNT
 func (m *Miniredis) cmdZcount(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -285,15 +261,7 @@ func (m *Miniredis) cmdZcount(c *server.Peer, cmd string, args []string) {
 
 // ZINCRBY
 func (m *Miniredis) cmdZincrby(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -332,15 +300,7 @@ func (m *Miniredis) makeCmdZinter(store bool) func(c *server.Peer, cmd string, a
 		if store {
 			minArgs++
 		}
-		if len(args) < minArgs {
-			setDirty(c)
-			c.WriteError(errWrongNumber(cmd))
-			return
-		}
-		if !m.handleAuth(c) {
-			return
-		}
-		if m.checkPubsub(c, cmd) {
+		if !m.isValidCMD(c, cmd, args, atLeast(minArgs)) {
 			return
 		}
 
@@ -513,15 +473,7 @@ func (m *Miniredis) makeCmdZinter(store bool) func(c *server.Peer, cmd string, a
 
 // ZLEXCOUNT
 func (m *Miniredis) cmdZlexcount(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -566,15 +518,7 @@ func (m *Miniredis) cmdZlexcount(c *server.Peer, cmd string, args []string) {
 
 // ZRANGE
 func (m *Miniredis) cmdZrange(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -668,15 +612,7 @@ func (m *Miniredis) cmdZrange(c *server.Peer, cmd string, args []string) {
 
 // ZREVRANGE
 func (m *Miniredis) cmdZrevrange(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -707,17 +643,10 @@ func (m *Miniredis) cmdZrevrange(c *server.Peer, cmd string, args []string) {
 // ZRANGEBYLEX and ZREVRANGEBYLEX
 func (m *Miniredis) makeCmdZrangebylex(reverse bool) server.Cmd {
 	return func(c *server.Peer, cmd string, args []string) {
-		if len(args) < 3 {
-			setDirty(c)
-			c.WriteError(errWrongNumber(cmd))
-			return
-		}
-		if !m.handleAuth(c) {
-			return
-		}
-		if m.checkPubsub(c, cmd) {
+		if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 			return
 		}
+
 		opts := optsRangeByLex{
 			Reverse: reverse,
 			Key:     args[0],
@@ -756,15 +685,7 @@ func (m *Miniredis) makeCmdZrangebylex(reverse bool) server.Cmd {
 // ZRANGEBYSCORE and ZREVRANGEBYSCORE
 func (m *Miniredis) makeCmdZrangebyscore(reverse bool) server.Cmd {
 	return func(c *server.Peer, cmd string, args []string) {
-		if len(args) < 3 {
-			setDirty(c)
-			c.WriteError(errWrongNumber(cmd))
-			return
-		}
-		if !m.handleAuth(c) {
-			return
-		}
-		if m.checkPubsub(c, cmd) {
+		if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 			return
 		}
 
@@ -808,15 +729,7 @@ func (m *Miniredis) makeCmdZrangebyscore(reverse bool) server.Cmd {
 // ZRANK and ZREVRANK
 func (m *Miniredis) makeCmdZrank(reverse bool) server.Cmd {
 	return func(c *server.Peer, cmd string, args []string) {
-		if len(args) < 2 {
-			setDirty(c)
-			c.WriteError(errWrongNumber(cmd))
-			return
-		}
-		if !m.handleAuth(c) {
-			return
-		}
-		if m.checkPubsub(c, cmd) {
+		if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 			return
 		}
 
@@ -878,15 +791,7 @@ func (m *Miniredis) makeCmdZrank(reverse bool) server.Cmd {
 
 // ZREM
 func (m *Miniredis) cmdZrem(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -917,15 +822,7 @@ func (m *Miniredis) cmdZrem(c *server.Peer, cmd string, args []string) {
 
 // ZREMRANGEBYLEX
 func (m *Miniredis) cmdZremrangebylex(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -973,15 +870,7 @@ func (m *Miniredis) cmdZremrangebylex(c *server.Peer, cmd string, args []string)
 
 // ZREMRANGEBYRANK
 func (m *Miniredis) cmdZremrangebyrank(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -1023,15 +912,7 @@ func (m *Miniredis) cmdZremrangebyrank(c *server.Peer, cmd string, args []string
 
 // ZREMRANGEBYSCORE
 func (m *Miniredis) cmdZremrangebyscore(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -1084,15 +965,7 @@ func (m *Miniredis) cmdZremrangebyscore(c *server.Peer, cmd string, args []strin
 
 // ZSCORE
 func (m *Miniredis) cmdZscore(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -1122,15 +995,7 @@ func (m *Miniredis) cmdZscore(c *server.Peer, cmd string, args []string) {
 
 // ZMSCORE
 func (m *Miniredis) cmdZMscore(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -1271,16 +1136,7 @@ func withLexRange(members []string, min string, minIncl bool, max string, maxInc
 
 // ZUNION
 func (m *Miniredis) cmdZunion(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -1348,15 +1204,7 @@ func (m *Miniredis) cmdZunion(c *server.Peer, cmd string, args []string) {
 
 // ZUNIONSTORE
 func (m *Miniredis) cmdZunionstore(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -1508,15 +1356,7 @@ func executeZUnion(db *RedisDB, opts zunionOptions) (sortedSet, error) {
 
 // ZSCAN
 func (m *Miniredis) cmdZscan(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -1680,15 +1520,7 @@ func (m *Miniredis) cmdZpopmax(reverse bool) server.Cmd {
 
 // ZRANDMEMBER
 func (m *Miniredis) cmdZrandmember(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
diff --git a/cmd_stream.go b/cmd_stream.go
index 7ce89d1..0167eaf 100644
--- a/cmd_stream.go
+++ b/cmd_stream.go
@@ -33,15 +33,7 @@ func commandsStream(m *Miniredis) {
 
 // XADD
 func (m *Miniredis) cmdXadd(c *server.Peer, cmd string, args []string) {
-	if len(args) < 4 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(4)) {
 		return
 	}
 
@@ -137,15 +129,7 @@ func (m *Miniredis) cmdXadd(c *server.Peer, cmd string, args []string) {
 
 // XLEN
 func (m *Miniredis) cmdXlen(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -171,9 +155,7 @@ func (m *Miniredis) cmdXlen(c *server.Peer, cmd string, args []string) {
 // XRANGE and XREVRANGE
 func (m *Miniredis) makeCmdXrange(reverse bool) server.Cmd {
 	return func(c *server.Peer, cmd string, args []string) {
-		if len(args) < 3 {
-			setDirty(c)
-			c.WriteError(errWrongNumber(cmd))
+		if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 			return
 		}
 		if len(args) == 4 || len(args) > 5 {
@@ -181,12 +163,6 @@ func (m *Miniredis) makeCmdXrange(reverse bool) server.Cmd {
 			c.WriteError(msgSyntaxError)
 			return
 		}
-		if !m.handleAuth(c) {
-			return
-		}
-		if m.checkPubsub(c, cmd) {
-			return
-		}
 
 		opts := struct {
 			key            string
@@ -320,15 +296,7 @@ func (m *Miniredis) makeCmdXrange(reverse bool) server.Cmd {
 
 // XGROUP
 func (m *Miniredis) cmdXgroup(c *server.Peer, cmd string, args []string) {
-	if len(args) == 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -513,15 +481,7 @@ func (m *Miniredis) cmdXgroupDelconsumer(c *server.Peer, cmd string, args []stri
 
 // XINFO
 func (m *Miniredis) cmdXinfo(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -684,15 +644,7 @@ func (m *Miniredis) sinceMilli(t time.Time) int {
 // XREADGROUP
 func (m *Miniredis) cmdXreadgroup(c *server.Peer, cmd string, args []string) {
 	// XREADGROUP GROUP group consumer STREAMS key ID
-	if len(args) < 6 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(6)) {
 		return
 	}
 
@@ -871,15 +823,7 @@ func xreadgroup(
 
 // XACK
 func (m *Miniredis) cmdXack(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -908,15 +852,7 @@ func (m *Miniredis) cmdXack(c *server.Peer, cmd string, args []string) {
 
 // XDEL
 func (m *Miniredis) cmdXdel(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -946,15 +882,7 @@ func (m *Miniredis) cmdXdel(c *server.Peer, cmd string, args []string) {
 
 // XREAD
 func (m *Miniredis) cmdXread(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -1128,15 +1056,7 @@ func writeXread(c *server.Peer, streams []string, res map[string][]StreamEntry)
 
 // XPENDING
 func (m *Miniredis) cmdXpending(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -1325,15 +1245,7 @@ func writeXpending(
 
 // XTRIM
 func (m *Miniredis) cmdXtrim(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -1431,15 +1343,7 @@ func (m *Miniredis) cmdXtrim(c *server.Peer, cmd string, args []string) {
 // XAUTOCLAIM
 func (m *Miniredis) cmdXautoclaim(c *server.Peer, cmd string, args []string) {
 	// XAUTOCLAIM key group consumer min-idle-time start
-	if len(args) < 5 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(5)) {
 		return
 	}
 
@@ -1596,15 +1500,7 @@ func writeXautoclaim(c *server.Peer, nextCallId string, res []StreamEntry, justI
 
 // XCLAIM
 func (m *Miniredis) cmdXclaim(c *server.Peer, cmd string, args []string) {
-	if len(args) < 5 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(5)) {
 		return
 	}
 
diff --git a/cmd_string.go b/cmd_string.go
index 08e6774..9e9b859 100644
--- a/cmd_string.go
+++ b/cmd_string.go
@@ -42,15 +42,7 @@ func commandsString(m *Miniredis) {
 
 // SET
 func (m *Miniredis) cmdSet(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -191,15 +183,7 @@ func (m *Miniredis) cmdSet(c *server.Peer, cmd string, args []string) {
 
 // SETEX
 func (m *Miniredis) cmdSetex(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -229,15 +213,7 @@ func (m *Miniredis) cmdSetex(c *server.Peer, cmd string, args []string) {
 
 // PSETEX
 func (m *Miniredis) cmdPsetex(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -270,15 +246,7 @@ func (m *Miniredis) cmdPsetex(c *server.Peer, cmd string, args []string) {
 
 // SETNX
 func (m *Miniredis) cmdSetnx(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -299,15 +267,7 @@ func (m *Miniredis) cmdSetnx(c *server.Peer, cmd string, args []string) {
 
 // MSET
 func (m *Miniredis) cmdMset(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -334,15 +294,7 @@ func (m *Miniredis) cmdMset(c *server.Peer, cmd string, args []string) {
 
 // MSETNX
 func (m *Miniredis) cmdMsetnx(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(2)) {
 		return
 	}
 
@@ -382,15 +334,7 @@ func (m *Miniredis) cmdMsetnx(c *server.Peer, cmd string, args []string) {
 
 // GET
 func (m *Miniredis) cmdGet(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -414,15 +358,7 @@ func (m *Miniredis) cmdGet(c *server.Peer, cmd string, args []string) {
 
 // GETEX
 func (m *Miniredis) cmdGetex(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -501,15 +437,7 @@ func (m *Miniredis) cmdGetex(c *server.Peer, cmd string, args []string) {
 
 // GETSET
 func (m *Miniredis) cmdGetset(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -538,15 +466,7 @@ func (m *Miniredis) cmdGetset(c *server.Peer, cmd string, args []string) {
 
 // GETDEL
 func (m *Miniredis) cmdGetdel(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -573,15 +493,7 @@ func (m *Miniredis) cmdGetdel(c *server.Peer, cmd string, args []string) {
 
 // MGET
 func (m *Miniredis) cmdMget(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -607,15 +519,7 @@ func (m *Miniredis) cmdMget(c *server.Peer, cmd string, args []string) {
 
 // INCR
 func (m *Miniredis) cmdIncr(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -639,15 +543,7 @@ func (m *Miniredis) cmdIncr(c *server.Peer, cmd string, args []string) {
 
 // INCRBY
 func (m *Miniredis) cmdIncrby(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -680,15 +576,7 @@ func (m *Miniredis) cmdIncrby(c *server.Peer, cmd string, args []string) {
 
 // INCRBYFLOAT
 func (m *Miniredis) cmdIncrbyfloat(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -720,15 +608,7 @@ func (m *Miniredis) cmdIncrbyfloat(c *server.Peer, cmd string, args []string) {
 
 // DECR
 func (m *Miniredis) cmdDecr(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -752,15 +632,7 @@ func (m *Miniredis) cmdDecr(c *server.Peer, cmd string, args []string) {
 
 // DECRBY
 func (m *Miniredis) cmdDecrby(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -793,15 +665,7 @@ func (m *Miniredis) cmdDecrby(c *server.Peer, cmd string, args []string) {
 
 // STRLEN
 func (m *Miniredis) cmdStrlen(c *server.Peer, cmd string, args []string) {
-	if len(args) != 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(1)) {
 		return
 	}
 
@@ -821,15 +685,7 @@ func (m *Miniredis) cmdStrlen(c *server.Peer, cmd string, args []string) {
 
 // APPEND
 func (m *Miniredis) cmdAppend(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -852,15 +708,7 @@ func (m *Miniredis) cmdAppend(c *server.Peer, cmd string, args []string) {
 
 // GETRANGE
 func (m *Miniredis) cmdGetrange(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -892,15 +740,7 @@ func (m *Miniredis) cmdGetrange(c *server.Peer, cmd string, args []string) {
 
 // SETRANGE
 func (m *Miniredis) cmdSetrange(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
@@ -943,15 +783,7 @@ func (m *Miniredis) cmdSetrange(c *server.Peer, cmd string, args []string) {
 
 // BITCOUNT
 func (m *Miniredis) cmdBitcount(c *server.Peer, cmd string, args []string) {
-	if len(args) < 1 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -1002,15 +834,7 @@ func (m *Miniredis) cmdBitcount(c *server.Peer, cmd string, args []string) {
 
 // BITOP
 func (m *Miniredis) cmdBitop(c *server.Peer, cmd string, args []string) {
-	if len(args) < 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(3)) {
 		return
 	}
 
@@ -1085,15 +909,7 @@ func (m *Miniredis) cmdBitop(c *server.Peer, cmd string, args []string) {
 
 // BITPOS
 func (m *Miniredis) cmdBitpos(c *server.Peer, cmd string, args []string) {
-	if len(args) < 2 || len(args) > 4 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, between(2, 4)) {
 		return
 	}
 
@@ -1186,15 +1002,7 @@ func (m *Miniredis) cmdBitpos(c *server.Peer, cmd string, args []string) {
 
 // GETBIT
 func (m *Miniredis) cmdGetbit(c *server.Peer, cmd string, args []string) {
-	if len(args) != 2 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(2)) {
 		return
 	}
 
@@ -1238,15 +1046,7 @@ func (m *Miniredis) cmdGetbit(c *server.Peer, cmd string, args []string) {
 
 // SETBIT
 func (m *Miniredis) cmdSetbit(c *server.Peer, cmd string, args []string) {
-	if len(args) != 3 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(3)) {
 		return
 	}
 
diff --git a/cmd_transactions.go b/cmd_transactions.go
index 94729e0..93d5354 100644
--- a/cmd_transactions.go
+++ b/cmd_transactions.go
@@ -17,14 +17,7 @@ func commandsTransaction(m *Miniredis) {
 
 // MULTI
 func (m *Miniredis) cmdMulti(c *server.Peer, cmd string, args []string) {
-	if len(args) != 0 {
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(0)) {
 		return
 	}
 
@@ -45,15 +38,7 @@ func (m *Miniredis) cmdMulti(c *server.Peer, cmd string, args []string) {
 
 // EXEC
 func (m *Miniredis) cmdExec(c *server.Peer, cmd string, args []string) {
-	if len(args) != 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(0)) {
 		return
 	}
 
@@ -99,15 +84,7 @@ func (m *Miniredis) cmdExec(c *server.Peer, cmd string, args []string) {
 
 // DISCARD
 func (m *Miniredis) cmdDiscard(c *server.Peer, cmd string, args []string) {
-	if len(args) != 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(0)) {
 		return
 	}
 
@@ -123,15 +100,7 @@ func (m *Miniredis) cmdDiscard(c *server.Peer, cmd string, args []string) {
 
 // WATCH
 func (m *Miniredis) cmdWatch(c *server.Peer, cmd string, args []string) {
-	if len(args) == 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, atLeast(1)) {
 		return
 	}
 
@@ -157,15 +126,7 @@ func (m *Miniredis) cmdWatch(c *server.Peer, cmd string, args []string) {
 
 // UNWATCH
 func (m *Miniredis) cmdUnwatch(c *server.Peer, cmd string, args []string) {
-	if len(args) != 0 {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
-		return
-	}
-	if !m.handleAuth(c) {
-		return
-	}
-	if m.checkPubsub(c, cmd) {
+	if !m.isValidCMD(c, cmd, args, exactly(0)) {
 		return
 	}
 
diff --git a/miniredis.go b/miniredis.go
index 33b31ee..72a145a 100644
--- a/miniredis.go
+++ b/miniredis.go
@@ -485,16 +485,16 @@ func exactly(n int) argRequirements {
 
 // isValidCMD returns true if command is valid and can be executed.
 func (m *Miniredis) isValidCMD(c *server.Peer, cmd string, args []string, argReqs argRequirements) bool {
-	if !m.handleAuth(c) {
+	if len(args) < argReqs.minimum || (argReqs.maximum != nil && len(args) > *argReqs.maximum) {
+		setDirty(c)
+		c.WriteError(errWrongNumber(cmd))
 		return false
 	}
-	if m.checkPubsub(c, cmd) {
+
+	if !m.handleAuth(c) {
 		return false
 	}
-
-	if len(args) < argReqs.minimum || (argReqs.maximum != nil && len(args) > *argReqs.maximum) {
-		setDirty(c)
-		c.WriteError(errWrongNumber(cmd))
+	if m.checkPubsub(c, cmd) {
 		return false
 	}