diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index d8adeecfda0..73b3b3ac190 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,7 @@
 Tue Mar  3 01:38:17 1998  Jason Merrill  <jason@yorick.cygnus.com>
 
+	* pt.c (unify): Don't allow reduced cv-quals when strict.
+
 	* call.c, class.c, pt.c, cp-tree.h: Remove nsubsts parm from
 	*type_unification* and unify.
 
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 3a3db96cce6..36f8aafa554 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5290,6 +5290,13 @@ unify (tparms, targs, ntparms, parm, arg, strict)
   if (arg == parm)
     return 0;
 
+  /* We can't remove cv-quals when strict.  */
+  if (strict && TREE_CODE (arg) == TREE_CODE (parm)
+      && TREE_CODE_CLASS (TREE_CODE (arg)) == 't'
+      && (TYPE_READONLY (arg) < TYPE_READONLY (parm)
+	  || TYPE_VOLATILE (arg) < TYPE_VOLATILE (parm)))
+    return 1;
+
   switch (TREE_CODE (parm))
     {
     case TYPENAME_TYPE: