diff --git a/lib/yaml/representer.py b/lib/yaml/representer.py
index 4ea8cb1f..f249f083 100644
--- a/lib/yaml/representer.py
+++ b/lib/yaml/representer.py
@@ -246,7 +246,7 @@ def represent_yaml_object(self, tag, data, cls, flow_style=None):
         return self.represent_mapping(tag, state, flow_style=flow_style)
 
     def represent_undefined(self, data):
-        raise RepresenterError("cannot represent an object: %s" % data)
+        raise RepresenterError("cannot represent an object", data)
 
 SafeRepresenter.add_representer(type(None),
         SafeRepresenter.represent_none)
@@ -411,7 +411,7 @@ def represent_object(self, data):
         elif hasattr(data, '__reduce__'):
             reduce = data.__reduce__()
         else:
-            raise RepresenterError("cannot represent object: %r" % data)
+            raise RepresenterError("cannot represent an object", data)
         reduce = (list(reduce)+[None]*5)[:5]
         function, args, state, listitems, dictitems = reduce
         args = list(args)
diff --git a/lib3/yaml/representer.py b/lib3/yaml/representer.py
index b9e65c51..483005f4 100644
--- a/lib3/yaml/representer.py
+++ b/lib3/yaml/representer.py
@@ -226,7 +226,7 @@ def represent_yaml_object(self, tag, data, cls, flow_style=None):
         return self.represent_mapping(tag, state, flow_style=flow_style)
 
     def represent_undefined(self, data):
-        raise RepresenterError("cannot represent an object: %s" % data)
+        raise RepresenterError("cannot represent an object", data)
 
 SafeRepresenter.add_representer(type(None),
         SafeRepresenter.represent_none)
@@ -316,7 +316,7 @@ def represent_object(self, data):
         elif hasattr(data, '__reduce__'):
             reduce = data.__reduce__()
         else:
-            raise RepresenterError("cannot represent object: %r" % data)
+            raise RepresenterError("cannot represent an object", data)
         reduce = (list(reduce)+[None]*5)[:5]
         function, args, state, listitems, dictitems = reduce
         args = list(args)