1 files changed, 7 insertions, 3 deletions
diff --git a/lib/sqlalchemy/ext/mutable.py b/lib/sqlalchemy/ext/mutable.py
index 7469bcbda..e49e9ea8b 100644
--- a/lib/sqlalchemy/ext/mutable.py
+++ b/lib/sqlalchemy/ext/mutable.py
@@ -621,16 +621,20 @@ class MutableDict(Mutable, dict):
         dict.__delitem__(self, key)
         self.changed()
 
+    def update(self, *a, **kw):
+        dict.update(self, *a, **kw)
+        self.changed()
+
     def clear(self):
         dict.clear(self)
         self.changed()
 
     @classmethod
     def coerce(cls, key, value):
-        """Convert plain dictionary to MutableDict."""
-        if not isinstance(value, MutableDict):
+        """Convert plain dictionary to instance of this class."""
+        if not isinstance(value, cls):
             if isinstance(value, dict):
-                return MutableDict(value)
+                return cls(value)
             return Mutable.coerce(key, value)
         else:
             return value