diff --git a/lib/galaxy/model/__init__.py b/lib/galaxy/model/__init__.py
index 2b931668a18d..6621cf23115b 100644
--- a/lib/galaxy/model/__init__.py
+++ b/lib/galaxy/model/__init__.py
@@ -6689,7 +6689,8 @@ def dataset_dbkeys_and_extensions_summary(self):
                             dbkeys.add(dbkey)
                     else:
                         dbkeys.add(dbkey_field)
-                    extensions.add(row.extension)
+                    if row.extension:
+                        extensions.add(row.extension)
             self._dataset_dbkeys_and_extensions_summary = (dbkeys, extensions)
         return self._dataset_dbkeys_and_extensions_summary