diff --git a/pywb/warcserver/handlers.py b/pywb/warcserver/handlers.py
index 8dc9ad47..69d7f210 100644
--- a/pywb/warcserver/handlers.py
+++ b/pywb/warcserver/handlers.py
@@ -86,7 +86,7 @@ class IndexHandler(object):
         if fields and isinstance(fields, str):
             fields = fields.split(',')
 
-        handler = self.OUTPUTS.get(output, fields)
+        handler = self.OUTPUTS.get(output)
         if not handler:
             errs = dict(last_exc=BadRequestException('output={0} not supported'.format(output)))
             return None, None, errs
diff --git a/tests/test_cdx_server_app.py b/tests/test_cdx_server_app.py
index 9f8c385a..b0c4ea3b 100644
--- a/tests/test_cdx_server_app.py
+++ b/tests/test_cdx_server_app.py
@@ -287,5 +287,13 @@ class TestCDXApp(BaseTestClass):
         for i in range(len(cdxes) - 1):
             assert cdxes[i]['timestamp'] >= cdxes[i + 1]['timestamp']
 
+    def test_error_unknown_output_format(self):
+        """test unknown output format in combination with a list of output fields"""
+        resp = self.query('http://www.iana.org/_css/2013.1/print.css',
+                          is_error=True,
+                          fields='urlkey,timestamp,status',
+                          output='foo')
+        assert resp.status_code == 400
+        assert resp.json == {'message': 'output=foo not supported'}