diff --git a/sys/arm/ti/am335x/am335x_dmtpps.c b/sys/arm/ti/am335x/am335x_dmtpps.c
index 2c4e634a4afc..db4de8a7760c 100644
--- a/sys/arm/ti/am335x/am335x_dmtpps.c
+++ b/sys/arm/ti/am335x/am335x_dmtpps.c
@@ -50,6 +50,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/kernel.h>
 #include <sys/module.h>
 #include <sys/malloc.h>
+#include <sys/mutex.h>
 #include <sys/rman.h>
 #include <sys/taskqueue.h>
 #include <sys/timepps.h>