--- a/setup.py	Tue Aug 24 11:25:25 2021 +0100
+++ b/setup.py	Tue Aug 24 11:27:45 2021 +0100
@@ -42,8 +42,9 @@
 			evv = int(evv)
 		except:
 			pass
-		if os.environ.get(ev,''):
-			DEFINE_MACROS.append((ev,evv))
+		else:
+			if evv:
+				DEFINE_MACROS.append((ev,evv))
 
 	#building pyRXP
 	if sys.platform=="win32":