diff --git a/runtime/src/mimalloc/c/include/mimalloc-types.h b/runtime/src/mimalloc/c/include/mimalloc-types.h
index bbb7bfdee18..cc8803aaf1a 100644
--- a/runtime/src/mimalloc/c/include/mimalloc-types.h
+++ b/runtime/src/mimalloc/c/include/mimalloc-types.h
@@ -17,7 +17,7 @@ terms of the MIT license. A copy of the license can be found in the file
 // ------------------------------------------------------
 
 // Define NDEBUG in the release version to disable assertions.
-#if !KONAN_MI_MALLOC
+#if KONAN_MI_MALLOC
   #define NDEBUG
 #endif