diff --git a/include/linux/mfd/mt6397/core.h b/include/linux/mfd/mt6397/core.h
index 9320c2a1e3e61..fc88d315bddeb 100644
--- a/include/linux/mfd/mt6397/core.h
+++ b/include/linux/mfd/mt6397/core.h
@@ -7,6 +7,8 @@
 #ifndef __MFD_MT6397_CORE_H__
 #define __MFD_MT6397_CORE_H__
 
+#include <linux/mutex.h>
+
 enum chip_id {
 	MT6323_CHIP_ID = 0x23,
 	MT6391_CHIP_ID = 0x91,