diff --git a/src/cmd/6c/cgen.c b/src/cmd/6c/cgen.c
index aba37b1b5c0..9e3e60e5024 100644
--- a/src/cmd/6c/cgen.c
+++ b/src/cmd/6c/cgen.c
@@ -32,6 +32,7 @@
 
 /* ,x/^(print|prtree)\(/i/\/\/ */
 int castup(Type*, Type*);
+int vaddr(Node *n, int a)
 
 void
 cgen(Node *n, Node *nn)