diff --git a/gcc/toplev.h b/gcc/toplev.h
index 46f7b3e2e30..4f4a0fe38e3 100644
--- a/gcc/toplev.h
+++ b/gcc/toplev.h
@@ -7,6 +7,7 @@
 
 #ifdef __STDC__
 union tree_node;
+struct rtx_def;
 #endif
 
 extern int count_error			PROTO ((int));