diff --git a/web.py b/web.py
index f9afa2c..032948a 100755
--- a/web.py
+++ b/web.py
@@ -12,7 +12,7 @@ def render():
     svg_stream = StringIO()
 
     adiffile = request.files.get('adif')
-    if adiffile and len(adiffile.filename) > 0:
+    if adiffile and adiffile.filename != "empty":
         if adiffile.filename[-4:] not in ['.adi', '.adf'] and adiffile.filename[-5:] not in ['.adif']:
             return "File extension not allowed."