diff --git a/src/calibre/ebooks/metadata/sources/identify.py b/src/calibre/ebooks/metadata/sources/identify.py
index 1c56dd4ef9..f92782bb3c 100644
--- a/src/calibre/ebooks/metadata/sources/identify.py
+++ b/src/calibre/ebooks/metadata/sources/identify.py
@@ -304,7 +304,7 @@ class ISBNMerge(object):
                     ans.pubdate = r.pubdate
                     break
             if getattr(ans.pubdate, 'year', None) == min_year:
-                min_date = datetime(min_year, ans.month, ans.day)
+                min_date = datetime(min_year, ans.pubdate.month, ans.pubdate.day)
             else:
                 min_date = datetime(min_year, 1, 2, tzinfo=utc_tz)
             ans.pubdate = min_date