diff --git a/lib/mhash_int.h b/lib/mhash_int.h
index c1ed1c9..6fe92a6 100644
--- a/lib/mhash_int.h
+++ b/lib/mhash_int.h
@@ -36,7 +36,7 @@ void *hmac_mhash_end(MHASH thread);
 
 /* Key generation functions */
 
-#define EMPTY_PROTOTYPES 1
+#undef EMPTY_PROTOTYPES
 
 #if defined(EMPTY_PROTOTYPES)