diff --git a/csrc/mm.h b/csrc/mm.h
index d9934f2a..64465405 100644
--- a/csrc/mm.h
+++ b/csrc/mm.h
@@ -3,6 +3,7 @@
 
 #include "mm_param.h"
 #include <stdint.h>
+#include <cstring>
 #include <queue>
 
 class mm_t