diff --git a/src/nonlinear.jl b/src/nonlinear.jl
index 870101de..9c3a77fe 100644
--- a/src/nonlinear.jl
+++ b/src/nonlinear.jl
@@ -31,7 +31,7 @@ Returns the SCIP expression pointer, whether the expression is a pure value (wit
 function push_expr!(
     nonlin::NonlinExpr,
     scip::Ptr{SCIP_},
-    vars::Dict{VarRef,Ref{Ptr{SCIP_VAR}}},
+    vars::Dict{VarRef,<:Ref{Ptr{SCIP_VAR}}},
     expr::Expr,
 )
     # Storage for SCIP_EXPR*
@@ -262,7 +262,7 @@ end
 function push_expr!(
     nonlin::NonlinExpr,
     scip::Ptr{SCIP_},
-    vars::Dict{VarRef,Ref{Ptr{SCIP_VAR}}},
+    vars::Dict{VarRef,<:Ref{Ptr{SCIP_VAR}}},
     expr::Number,
 )
     # Storage for SCIP_EXPR*
diff --git a/src/scip_data.jl b/src/scip_data.jl
index dbb1fef5..9d8b22e8 100644
--- a/src/scip_data.jl
+++ b/src/scip_data.jl
@@ -31,9 +31,9 @@ SCIPData holds pointers to SCIP data.
 It does not perform memory management and should not be created directly.
 """
 mutable struct SCIPData
-    scip::Ref{Ptr{SCIP_}}
-    vars::Dict{VarRef,Ref{Ptr{SCIP_VAR}}}
-    conss::Dict{ConsRef,Ref{Ptr{SCIP_CONS}}}
+    scip::Base.RefValue{Ptr{SCIP_}}
+    vars::Dict{VarRef,Base.RefValue{Ptr{SCIP_VAR}}}
+    conss::Dict{ConsRef,Base.RefValue{Ptr{SCIP_CONS}}}
 
     var_count::Int64
     cons_count::Int64
@@ -69,8 +69,8 @@ mutable struct SCIPData
         @SCIP_CALL SCIPcreateProbBasic(scip[], "")
         scip_data = new(
             scip,
-            Dict{VarRef,Ref{Ptr{SCIP_VAR}}}(),
-            Dict{ConsRef,Ref{Ptr{SCIP_CONS}}}(),
+            Dict{VarRef,Base.RefValue{Ptr{SCIP_VAR}}}(),
+            Dict{ConsRef,Base.RefValue{Ptr{SCIP_CONS}}}(),
             0,
             0,
             Dict{Any,Ptr{SCIP_CONSHDLR}}(),
diff --git a/src/sepa.jl b/src/sepa.jl
index 3e7455af..78bb5d16 100644
--- a/src/sepa.jl
+++ b/src/sepa.jl
@@ -215,7 +215,7 @@ associated to the separator `sepa`.
 """
 function add_cut_sepa(
     scip::Ptr{SCIP_},
-    vars::Dict{VarRef,Ref{Ptr{SCIP_VAR}}},
+    vars::Dict{VarRef,<:Ref{Ptr{SCIP_VAR}}},
     sepas::Dict{Any,Ptr{SCIP_SEPA}},
     sepa::SEPA,
     varrefs,