Index: sys/mips/atheros/ar531x/ar5315_machdep.c
===================================================================
--- sys/mips/atheros/ar531x/ar5315_machdep.c
+++ sys/mips/atheros/ar531x/ar5315_machdep.c
@@ -40,6 +40,7 @@
 #include <sys/kdb.h>
 #include <sys/reboot.h>
 #include <sys/boot.h>
+#include <sys/mutex.h>
 
 #include <vm/vm.h>
 #include <vm/vm_page.h>