diff --git a/sys/sys/rwlock.h b/sys/sys/rwlock.h
index 4444e363c7fe..f5dd53c112aa 100644
--- a/sys/sys/rwlock.h
+++ b/sys/sys/rwlock.h
@@ -36,6 +36,7 @@
 #include <sys/_rwlock.h>
 
 #ifdef _KERNEL
+#include <sys/pcpu.h>
 #include <machine/atomic.h>
 #endif