diff --git a/warcprox/dedup.py b/warcprox/dedup.py
index d1e456d..9774c6a 100644
--- a/warcprox/dedup.py
+++ b/warcprox/dedup.py
@@ -292,7 +292,7 @@ class TroughDedupDb(object):
             return None
 
     def notify(self, recorded_url, records):
-        if (records[0].get_header(warctools.WarcRecord.TYPE) == warctools.WarcRecord.RESPONSE
+        if (records and records[0].type == b'response'
                 and recorded_url.response_recorder.payload_size() > 0):
             digest_key = warcprox.digest_str(
                     recorded_url.payload_digest,