diff --git a/hphp/runtime/ext/std/ext_std_file.h b/hphp/runtime/ext/std/ext_std_file.h
index a79d8c0223e75..bc5ebeb0612fa 100644
--- a/hphp/runtime/ext/std/ext_std_file.h
+++ b/hphp/runtime/ext/std/ext_std_file.h
@@ -20,6 +20,8 @@
 
 #include "hphp/runtime/base/base-includes.h"
 
+#undef basename
+
 namespace HPHP {
 ///////////////////////////////////////////////////////////////////////////////
 // constants