--- b/cut-n-paste/synctex/synctex_parser.c
+++ a/cut-n-paste/synctex/synctex_parser.c
@@ -83,11 +83,6 @@
  *  First level objects are sheets and forms, containing boxes, glues, kerns...
  *  The third tree allows to browse leaves according to tag and line.
  */
-/* Declare _GNU_SOURCE for accessing vasprintf. For MSC compiler, vasprintf is
- * defined in this file
- */
-#define _GNU_SOURCE
-
 #   if defined(SYNCTEX_USE_LOCAL_HEADER)
 #       include "synctex_parser_local.h"
 #   else
@@ -100,6 +95,7 @@
 #       endif
 #   endif
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>