diff --git a/src/lisp/validate.h b/src/lisp/validate.h
index 784258e3efb705222155fee8c4dd208298744624..7f1c0e0c70a129825b17c62ce8dba895f8e4e59e 100644
--- a/src/lisp/validate.h
+++ b/src/lisp/validate.h
@@ -37,5 +37,6 @@
 #endif
 
 extern void validate(void);
+extern void validate_stacks(void);
 
 #endif /* _VALIDATE_H_ */