diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 24a3a39c27..6e959b8c7a 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -170,7 +170,7 @@ loop:
 void
 indir(Node *nl, Node *nr)
 {
-	if(nr != N)
+	if(nr != N && nl != nr)
 		*nl = *nr;
 }