diff --git a/git-filter-repo b/git-filter-repo
index 22826b5..1696a6c 100755
--- a/git-filter-repo
+++ b/git-filter-repo
@@ -320,8 +320,8 @@ class MailmapInfo(object):
     for old, new in self.changes.items():
       old_name, old_email = old
       new_name, new_email = new
-      if (not old_email or email.lower() == old_email.lower()) and (
-          name  == old_name or not old_name):
+      if (old_email is None or email.lower() == old_email.lower()) and (
+          name == old_name or not old_name):
         return (new_name or name, new_email or email)
     return (name, email)