Rename DEBUG macro to Py_DEBUG
diff --git a/Parser/pgen.c b/Parser/pgen.c
index c5a0618..9668630 100644
--- a/Parser/pgen.c
+++ b/Parser/pgen.c
@@ -166,7 +166,7 @@
 	return nf;
 }
 
-#ifdef DEBUG
+#ifdef Py_DEBUG
 
 static char REQNFMT[] = "metacompile: less than %d children\n";