--- a/tincan.py	Wed May 29 09:40:32 2019 -0700
+++ b/tincan.py	Wed May 29 09:47:27 2019 -0700
@@ -449,7 +449,7 @@
         ims = bottle.request.environ.get('HTTP_IF_MODIFIED_SINCE')
         if ims:
             ims = self._parse_date(ims.split(";")[0].strip())
-        if ims is not None and ims >= int(stats.st_mtime):
+        if ims is not None and ims >= int(mtime):
             headers["Content-Length"] = "0"
             return bottle.HTTPResponse(body=b"", status=304, headers=headers)
         # Standard response.