diff --git a/lib/extras.py b/lib/extras.py
index 491a3908..d8a4bfef 100644
--- a/lib/extras.py
+++ b/lib/extras.py
@@ -841,8 +841,8 @@ class CompositeCaster(object):
         tokens = self.tokenize(s)
         if len(tokens) != len(self.atttypes):
             raise psycopg2.DataError(
-                "expecting %d components for the type %s, %d found instead",
-                (len(self.atttypes), self.name, len(self.tokens)))
+                "expecting %d components for the type %s, %d found instead" %
+                (len(self.atttypes), self.name, len(tokens)))
 
         attrs = [ curs.cast(oid, token)
             for oid, token in zip(self.atttypes, tokens) ]
diff --git a/tests/test_types_extras.py b/tests/test_types_extras.py
index 9936305b..b77e7acd 100755
--- a/tests/test_types_extras.py
+++ b/tests/test_types_extras.py
@@ -648,6 +648,16 @@ class AdaptTypeTestCase(unittest.TestCase):
         self.assertEqual(v[1][1], "world")
         self.assertEqual(v[1][2], date(2011,1,3))
 
+    @skip_if_no_composite
+    def test_wrong_schema(self):
+        oid = self._create_type("type_ii", [("a", "integer"), ("b", "integer")])
+        from psycopg2.extras import CompositeCaster
+        c = CompositeCaster('type_ii', oid, [('a', 23), ('b', 23), ('c', 23)])
+        curs = self.conn.cursor()
+        psycopg2.extensions.register_type(c.typecaster, curs)
+        curs.execute("select (1,2)::type_ii")
+        self.assertRaises(psycopg2.DataError, curs.fetchone)
+
     def _create_type(self, name, fields):
         curs = self.conn.cursor()
         try: