diff --git a/Parser/pgen.c b/Parser/pgen.c
index 55ce7a1..03d3c82 100644
--- a/Parser/pgen.c
+++ b/Parser/pgen.c
@@ -13,6 +13,7 @@
 #include "pgen.h"
 
 extern int Py_DebugFlag;
+int Py_IgnoreEnvironmentFlag; /* needed by Py_GETENV */
 
 
 /* PART ONE -- CONSTRUCT NFA -- Cf. Algorithm 3.2 from [Aho&Ullman 77] */