diff --git a/sys/sys/un.h b/sys/sys/un.h
index c3c4b71fe..537149225 100644
--- a/sys/sys/un.h
+++ b/sys/sys/un.h
@@ -16,6 +16,7 @@ typedef __sa_family_t	sa_family_t;
  * Definitions for UNIX IPC domain.
  */
 struct	sockaddr_un {
+	uint8_t		sun_len;
 	sa_family_t	sun_family;
 	char		sun_path[UNIX_PATH_MAX];
 };
diff --git a/test/test56.c b/test/test56.c
index fb13872c4..6b46d9fdf 100644
--- a/test/test56.c
+++ b/test/test56.c
@@ -302,8 +302,8 @@ void test_header(void)
 	sun.sun_path[2] = 'x';
 	sun.sun_path[3] = '\0';
 
-	if (SUN_LEN(&sun) != 4) {
-		test_fail("SUN_LEN(&sun) should be 4");
+	if (SUN_LEN(&sun) != 5) {
+		test_fail("SUN_LEN(&sun) should be 5");
 	}
 
 	if (PF_UNIX != PF_LOCAL || PF_UNIX != PF_FILE || PF_UNIX != AF_UNIX) {