diff --git a/sys/opencrypto/xform_aes_xts.c b/sys/opencrypto/xform_aes_xts.c
index 096a87b8b924..0b415f1d6346 100644
--- a/sys/opencrypto/xform_aes_xts.c
+++ b/sys/opencrypto/xform_aes_xts.c
@@ -50,6 +50,7 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/types.h>
 #include <opencrypto/xform_enc.h>
 
 static	int aes_xts_setkey(void *, const uint8_t *, int);