diff --git a/modules/database/src/ioc/db/dbLockPvt.h b/modules/database/src/ioc/db/dbLockPvt.h
index 520241c3e..99ab590df 100644
--- a/modules/database/src/ioc/db/dbLockPvt.h
+++ b/modules/database/src/ioc/db/dbLockPvt.h
@@ -10,6 +10,7 @@
 #define DBLOCKPVT_H
 
 #include "dbLock.h"
+#include "epicsMutex.h"
 #include "epicsSpin.h"
 
 /* Define to enable additional error checking */