diff --git a/sys/sys/_pv_entry.h b/sys/sys/_pv_entry.h
index 3cd0d9c687f6..ec3ea24a21a5 100644
--- a/sys/sys/_pv_entry.h
+++ b/sys/sys/_pv_entry.h
@@ -36,6 +36,8 @@
 #ifndef __SYS__PV_ENTRY_H__
 #define	__SYS__PV_ENTRY_H__
 
+#include <sys/param.h>
+
 struct pmap;
 
 /*