diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 356f3d6f52b5..3adf9e0a1aba 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -218,7 +218,8 @@ lookup_base (tree t, tree base, base_access access, base_kind *kind_ptr)
 
   /* If BASE is incomplete, it can't be a base of T--and instantiating it
      might cause an error.  */
-  if (t_binfo && (COMPLETE_TYPE_P (base) || TYPE_BEING_DEFINED (base)))
+  if (t_binfo && CLASS_TYPE_P (base)
+      && (COMPLETE_TYPE_P (base) || TYPE_BEING_DEFINED (base)))
     {
       struct lookup_base_data_s data;