diff --git a/core/sound/ym3438.c b/core/sound/ym3438.c
index 8a9d328..5dd8b42 100644
--- a/core/sound/ym3438.c
+++ b/core/sound/ym3438.c
@@ -42,6 +42,7 @@
  * version: 1.0.2
  */
 
+#include <string.h>
 #include "ym3438.h"
 
 enum {