diff --git a/src/V3Param.cpp b/src/V3Param.cpp
index b10521f90..977a0a803 100644
--- a/src/V3Param.cpp
+++ b/src/V3Param.cpp
@@ -546,6 +546,9 @@ class ParamProcessor final {
     }
     void replaceRefsRecurse(AstNode* const nodep, const AstClass* const oldClassp,
                             AstClass* const newClassp) {
+        // Some of the nodes may be already marked as visited, because they were copied. They
+        // should be marked as unvisited, because parameterized references have to be handled.
+        nodep->user5(false);
         if (AstClassRefDType* const classRefp = VN_CAST(nodep, ClassRefDType)) {
             if (classRefp->classp() == oldClassp) classRefp->classp(newClassp);
         } else if (AstClassOrPackageRef* const classRefp = VN_CAST(nodep, ClassOrPackageRef)) {
diff --git a/test_regress/t/t_class_param_type.v b/test_regress/t/t_class_param_type.v
index 45a1b78ed..31402e10a 100644
--- a/test_regress/t/t_class_param_type.v
+++ b/test_regress/t/t_class_param_type.v
@@ -27,6 +27,23 @@ endclass
 typedef Cls cls_t;
 typedef cls_t cls2_t;
 
+class Singleton #(type T=int);
+   static function Singleton#(T) self;
+      Singleton#(T) c = new;
+      return c;
+   endfunction
+   function int get_size;
+      return $bits(T);
+   endfunction
+endclass
+
+class SingletonUnusedDefault #(type T=int);
+   static function SingletonUnusedDefault#(T) self;
+      SingletonUnusedDefault#(T) c = new;
+      return c;
+   endfunction
+endclass
+
 module t (/*AUTOARG*/);
 
    initial begin
@@ -37,11 +54,25 @@ module t (/*AUTOARG*/);
       automatic Parcls#(cls_t) p2 = p1;
       automatic Parcls#(cls2_t) p3 = p2;
 
+      automatic Singleton #(int) s_int1 = Singleton#(int)::self();
+      automatic Singleton #(int) s_int2 = Singleton#(int)::self();
+      automatic Singleton #(bit) s_bit1 = Singleton#(bit)::self();
+      automatic Singleton #(bit) s_bit2 = Singleton#(bit)::self();
+      automatic SingletonUnusedDefault #(bit) sud1 = SingletonUnusedDefault#(bit)::self();
+      automatic SingletonUnusedDefault #(bit) sud2 = SingletonUnusedDefault#(bit)::self();
+
       if (pdt1 != pdt2) $stop;
       if (pdt2 != pdt3) $stop;
       if (p1 != p2) $stop;
       if (p2 != p3) $stop;
 
+      if (s_int1 != s_int2) $stop;
+      if (s_bit1 != s_bit2) $stop;
+      if (sud1 != sud2) $stop;
+
+      if (s_int1.get_size() != 32) $stop;
+      if (s_bit1.get_size() != 1) $stop;
+
       if (p1.get_p() != 20) $stop;
       if (pdt1.get_p() != 20) $stop;
       if (Parcls#(cls2_t)::get_p() != 20) $stop;