diff -r ab13c1d0d5e6 Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Sat Oct 15 19:03:06 2016 -0700
+++ b/Objects/unicodeobject.c	Sun Oct 16 17:31:47 2016 +0800
@@ -3215,7 +3215,7 @@
                      "'%.400s' decoder returned '%.400s' instead of 'str'; "
                      "use codecs.decode() to decode to arbitrary types",
                      encoding,
-                     Py_TYPE(unicode)->tp_name, Py_TYPE(unicode)->tp_name);
+                     Py_TYPE(unicode)->tp_name);
         Py_DECREF(unicode);
         goto onError;
     }
@@ -3276,7 +3276,7 @@
                      "'%.400s' decoder returned '%.400s' instead of 'str'; "
                      "use codecs.decode() to decode to arbitrary types",
                      encoding,
-                     Py_TYPE(unicode)->tp_name, Py_TYPE(unicode)->tp_name);
+                     Py_TYPE(unicode)->tp_name);
         Py_DECREF(v);
         goto onError;
     }
@@ -3622,7 +3622,7 @@
                  "'%.400s' encoder returned '%.400s' instead of 'bytes'; "
                  "use codecs.encode() to encode to arbitrary types",
                  encoding,
-                 Py_TYPE(v)->tp_name, Py_TYPE(v)->tp_name);
+                 Py_TYPE(v)->tp_name);
     Py_DECREF(v);
     return NULL;
 }
@@ -3651,7 +3651,7 @@
                      "'%.400s' encoder returned '%.400s' instead of 'str'; "
                      "use codecs.encode() to encode to arbitrary types",
                      encoding,
-                     Py_TYPE(v)->tp_name, Py_TYPE(v)->tp_name);
+                     Py_TYPE(v)->tp_name);
         Py_DECREF(v);
         goto onError;
     }