diff --git a/util/ncgg/output.c b/util/ncgg/output.c
index b836f4507..c7997a3bb 100644
--- a/util/ncgg/output.c
+++ b/util/ncgg/output.c
@@ -855,6 +855,7 @@ used(resource,use,max) char *resource; {
 
 statistics() {
 	extern char *end,*sbrk();
+	extern int nnodes, maxempatlen,maxrule;
 
 	used("Registers",nregs,MAXREGS);
 	used("Properties",nprops,MAXPROPS);