diff --git a/src/lib/w32/posixfile.c b/src/lib/w32/posixfile.c
index e6338296..5b21d696 100644
--- a/src/lib/w32/posixfile.c
+++ b/src/lib/w32/posixfile.c
@@ -30,6 +30,8 @@
  *  Known contributors to this file:
  *     Ron Koenderink, 2007
  */
+
+#include <config.h>
 #include <direct.h>
 #include <io.h>
 #include "unistd.h"