Index: gcc/fortran/interface.c
===================================================================
--- gcc/fortran/interface.c	(revision 201221)
+++ gcc/fortran/interface.c	(working copy)
@@ -1966,7 +1966,8 @@ compare_parameter (gfc_symbol *formal, gfc_expr *a
     }
 
   /* F2008, 12.5.2.5; IR F08/0073.  */
-  if (formal->ts.type == BT_CLASS && actual->expr_type != EXPR_NULL
+  if (formal->ts.type == BT_CLASS && formal->attr.class_ok
+      && actual->expr_type != EXPR_NULL
       && ((CLASS_DATA (formal)->attr.class_pointer
 	   && !formal->attr.intent == INTENT_IN)
           || CLASS_DATA (formal)->attr.allocatable))
@@ -1978,6 +1979,10 @@ compare_parameter (gfc_symbol *formal, gfc_expr *a
 			formal->name, &actual->where);
 	  return 0;
 	}
+
+      if (!gfc_expr_attr (actual).class_ok)
+	return 0;
+
       if (!gfc_compare_derived_types (CLASS_DATA (actual)->ts.u.derived,
 				      CLASS_DATA (formal)->ts.u.derived))
 	{
Index: gcc/fortran/simplify.c
===================================================================
--- gcc/fortran/simplify.c	(revision 201221)
+++ gcc/fortran/simplify.c	(working copy)
@@ -2300,7 +2300,8 @@ gfc_simplify_same_type_as (gfc_expr *a, gfc_expr *
 
   /* Return .false. if the dynamic type can never be the
      same.  */
-  if ((a->ts.type == BT_CLASS || b->ts.type == BT_CLASS)
+  if (((a->ts.type == BT_CLASS && gfc_expr_attr (a).class_ok)
+       || (b->ts.type == BT_CLASS && gfc_expr_attr (b).class_ok))
       && !gfc_type_compatible (&a->ts, &b->ts)
       && !gfc_type_compatible (&b->ts, &a->ts))
     return gfc_get_logical_expr (gfc_default_logical_kind, &a->where, false);