diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b628c262..c7b3ef7d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -49,7 +49,7 @@ jobs:
             sudo ./llvm.sh 17
       shell: bash
     - name: default build
-      run: make
+      run: make -j$(nproc)
     - name: check + tests
       run: |
             make check -j$(nproc)
@@ -65,7 +65,7 @@ jobs:
             make distclean && make ENABLE_SDL=0 check -j$(nproc)
     - name: gdbstub test
       run: |
-            make distclean ENABLE_GDBSTUB=1 gdbstub-test
+            make distclean && make ENABLE_GDBSTUB=1 gdbstub-test -j$(nproc)
     - name: JIT test
       run: |
             make ENABLE_JIT=1 clean && make ENABLE_JIT=1 check -j$(nproc)
diff --git a/Makefile b/Makefile
index 4aa1411b..1ce6c5bc 100644
--- a/Makefile
+++ b/Makefile
@@ -124,8 +124,6 @@ src/mini-gdbstub/Makefile:
 GDBSTUB_LIB := $(GDBSTUB_OUT)/libgdbstub.a
 $(GDBSTUB_LIB): src/mini-gdbstub/Makefile
 	$(MAKE) -C $(dir $<) O=$(dir $@)
-# FIXME: track gdbstub dependency properly
-$(OUT)/decode.o: $(GDBSTUB_LIB)
 OBJS_EXT += gdbstub.o breakpoint.o
 CFLAGS += -D'GDBSTUB_COMM="$(GDBSTUB_COMM)"'
 LDFLAGS += $(GDBSTUB_LIB) -pthread
@@ -219,6 +217,10 @@ ifeq ($(call has, EXT_F), 1)
 $(OBJS): $(SOFTFLOAT_LIB)
 endif
 
+ifeq ($(call has, GDBSTUB), 1)
+$(OBJS): $(GDBSTUB_LIB)
+endif
+
 $(OUT)/%.o: src/%.c $(deps_emcc)
 	$(VECHO) "  CC\t$@\n"
 	$(Q)$(CC) -o $@ $(CFLAGS) $(CFLAGS_emcc) -c -MMD -MF $@.d $<