diff --git a/ext/posix/posix.c b/ext/posix/posix.c
index 4196a753a72..01afc91cd36 100644
--- a/ext/posix/posix.c
+++ b/ext/posix/posix.c
@@ -468,7 +468,7 @@ PHP_FUNCTION(posix_uname)
 	add_assoc_string(return_value, "release",  u.release,  1);
 	add_assoc_string(return_value, "version",  u.version,  1);
 	add_assoc_string(return_value, "machine",  u.machine,  1);
-#ifdef _GNU_SOURCE
+#if defined(_GNU_SOURCE) && !defined(DARWIN)
 	add_assoc_string(return_value, "domainname", u.domainname, 1);
 #endif
 }