diff --git a/gio/gunixsocketaddress.c b/gio/gunixsocketaddress.c
index b0d3c8fe4..27e195e47 100644
--- a/gio/gunixsocketaddress.c
+++ b/gio/gunixsocketaddress.c
@@ -66,7 +66,9 @@ enum
   PROP_ADDRESS_TYPE
 };
 
+#ifndef UNIX_PATH_MAX
 #define UNIX_PATH_MAX sizeof (((struct sockaddr_un *) 0)->sun_path)
+#endif
 
 struct _GUnixSocketAddressPrivate
 {