diff --git a/src/frontend/moduleTypechecker.ml b/src/frontend/moduleTypechecker.ml
index cd08d0ccc..c579ec554 100644
--- a/src/frontend/moduleTypechecker.ml
+++ b/src/frontend/moduleTypechecker.ml
@@ -765,14 +765,12 @@ and typecheck_binding (config : typecheck_config) (tyenv : Typeenv.t) (utbind :
               in
               return ([ Rec(recbindacc |> Alist.to_list) ], ssig)
 
-          | UTMutable((rng, varnm) as var, utastI) ->
-              let* (eI, tyI) = Typechecker.typecheck { pre with quantifiability = Unquantifiable; } tyenv utastI in
-              let evid = EvalVarID.fresh var in
-              let pty = TypeConv.lift_poly (rng, RefType(tyI)) in
+          | UTMutable(ident, utastI) ->
+              let* (varnm, pty_ref, evid, eI) = Typechecker.typecheck_let_mutable pre tyenv ident utastI in
               let ssig =
                 let ventry =
                   {
-                    val_type  = pty;
+                    val_type  = pty_ref;
                     val_name  = Some(evid);
                     val_stage = pre.stage;
                   }
diff --git a/src/frontend/typechecker.mli b/src/frontend/typechecker.mli
index 600743785..70d9e0078 100644
--- a/src/frontend/typechecker.mli
+++ b/src/frontend/typechecker.mli
@@ -9,6 +9,8 @@ val typecheck_letrec : pre -> type_environment -> untyped_let_binding list -> ((
 
 val typecheck_nonrec : always_polymorphic:bool -> pre -> type_environment -> untyped_let_binding -> (var_name * poly_type * EvalVarID.t * abstract_tree, type_error) result
 
+val typecheck_let_mutable : pre -> type_environment -> var_name ranged -> untyped_abstract_tree -> (var_name * poly_type * EvalVarID.t * abstract_tree, type_error) result
+
 val main : typecheck_config -> stage -> Typeenv.t -> untyped_abstract_tree -> (mono_type * abstract_tree, type_error) result
 
 val are_unifiable : mono_type -> mono_type -> bool