diff --git a/simclist.c b/simclist.c
index 1b8d3c8..0805330 100755
--- a/simclist.c
+++ b/simclist.c
@@ -44,8 +44,10 @@
 
 /* disable asserts */
 #ifndef SIMCLIST_DEBUG
+#ifndef NDEBUG
 #define NDEBUG
 #endif
+#endif
 
 #include <assert.h>