diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 7a370367c426..79dce7482ac3 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2007-01-05  Douglas Gregor  <doug.gregor@gmail.com>
+
+	* pt.c (tsubst): Propagate the need for structural equality checks
+	when reducing the level of template parameters.
+
 2007-01-03  Kazu Hirata  <kazu@codesourcery.com>
 
 	* pt.c: Fix a comment typo.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c1fc2ad4f46b..787cd60b060e 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -7530,6 +7530,8 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 		     require structural equality checking to compare
 		     TEMPLATE_TEMPLATE_PARMs. */
 		  SET_TYPE_STRUCTURAL_EQUALITY (r);
+		else if (TYPE_STRUCTURAL_EQUALITY_P (t))
+		  SET_TYPE_STRUCTURAL_EQUALITY (r);
 		else
 		  TYPE_CANONICAL (r) = canonical_type_parameter (r);