diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e4e6446ed52..1ec3c639554 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2010-10-26  Jason Merrill  <jason@redhat.com>
 
+	* pt.c (lookup_template_class): push_tinst_level around call to
+	coerce_template_parms.
+
 	* tree.c (stabilize_expr): Handle xvalues properly.
 
 	* call.c (build_over_call): Use argarray[0] for 'this' argument.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 1de5d5527fd..f150d8f6130 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -6595,13 +6595,17 @@ lookup_template_class (tree d1,
 	  arglist = bound_args;
 	}
       else
-	arglist
-	  = coerce_template_parms (INNERMOST_TEMPLATE_PARMS (parmlist),
-				   INNERMOST_TEMPLATE_ARGS (arglist),
-				   gen_tmpl,
-				   complain,
-				   /*require_all_args=*/true,
-				   /*use_default_args=*/true);
+	{
+	  push_tinst_level (templ);
+	  arglist
+	    = coerce_template_parms (INNERMOST_TEMPLATE_PARMS (parmlist),
+				     INNERMOST_TEMPLATE_ARGS (arglist),
+				     gen_tmpl,
+				     complain,
+				     /*require_all_args=*/true,
+				     /*use_default_args=*/true);
+	  pop_tinst_level ();
+	}
 
       if (arglist == error_mark_node)
 	/* We were unable to bind the arguments.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b048d8ce276..a00180a3d31 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2010-10-26  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/template/arg8.C: Test for helpful diagnostic.
+
 2010-10-26  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/42647
diff --git a/gcc/testsuite/g++.dg/template/arg8.C b/gcc/testsuite/g++.dg/template/arg8.C
new file mode 100644
index 00000000000..5b3a31cc00b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/arg8.C
@@ -0,0 +1,12 @@
+// Test for a message indicating what template we're trying to convert
+// arguments for.  We can't actually test for it directly because it
+// doesn't have an associated line number, but we can test for the
+// "instantiated from here" message that follows.
+
+template <int I>
+struct A { };
+
+int i;
+A<i> a;				// { dg-message "instantiated from here" }
+// { dg-error "not a valid template argument" "" { target *-*-* } 10 }
+// { dg-error "invalid type in declaration" "" { target *-*-* } 10 }