1 files changed, 14 insertions, 0 deletions
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 6520be202..6eb4367b3 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -5292,6 +5292,20 @@ class Update(ValuesBase):
         else:
             self._whereclause = _literal_as_text(whereclause)
 
+    @property
+    def _extra_froms(self):
+        # TODO: this could be made memoized
+        # if the memoization is reset on each generative call.
+        froms = []
+        seen = set([self.table])
+
+        if self._whereclause is not None:
+            for item in _from_objects(self._whereclause):
+                if not seen.intersection(item._cloned_set):
+                    froms.append(item)
+                seen.update(item._cloned_set)
+
+        return froms
 
 class Delete(UpdateBase):
     """Represent a DELETE construct.