diff --git a/include/sys/types.h b/include/sys/types.h
index c4390334b4..c4048845af 100644
--- a/include/sys/types.h
+++ b/include/sys/types.h
@@ -1,5 +1,6 @@
 #ifndef _SYS_TYPES_H
 #define _SYS_TYPES_H
+#include <stddef.h>
 
 typedef long blksize_t;
 typedef long dev_t;