diff -r 897fe8fa14b5 Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Thu Oct 13 23:00:37 2016 -0700
+++ b/Objects/unicodeobject.c	Fri Oct 14 17:27:24 2016 +0800
@@ -3400,11 +3400,9 @@
 {
     Py_ssize_t wlen, wlen2;
     wchar_t *wstr;
-    PyObject *bytes = NULL;
     char *errmsg;
-    PyObject *reason = NULL;
-    PyObject *exc;
-    size_t error_pos;
+    PyObject *bytes, *reason, *exc;
+    size_t error_pos, errlen;
     int surrogateescape;
 
     if (locale_error_handler(errors, &surrogateescape) < 0)
@@ -3459,6 +3457,7 @@
 
         len2 = wcstombs(PyBytes_AS_STRING(bytes), wstr, len+1);
         if (len2 == (size_t)-1 || len2 > len) {
+            Py_DECREF(bytes);
             error_pos = (size_t)-1;
             goto encode_error;
         }
@@ -3474,17 +3473,15 @@
         error_pos = wcstombs_errorpos(wstr);
 
     PyMem_Free(wstr);
-    Py_XDECREF(bytes);
-
-    if (errmsg != NULL) {
-        size_t errlen;
-        wstr = Py_DecodeLocale(errmsg, &errlen);
-        if (wstr != NULL) {
-            reason = PyUnicode_FromWideChar(wstr, errlen);
-            PyMem_RawFree(wstr);
-        } else
-            errmsg = NULL;
-    }
+
+    wstr = Py_DecodeLocale(errmsg, &errlen);
+    if (wstr != NULL) {
+        reason = PyUnicode_FromWideChar(wstr, errlen);
+        PyMem_RawFree(wstr);
+    } else {
+        errmsg = NULL;
+    }
+
     if (errmsg == NULL)
         reason = PyUnicode_FromString(
             "wcstombs() encountered an unencodable "
@@ -3500,7 +3497,7 @@
     Py_DECREF(reason);
     if (exc != NULL) {
         PyCodec_StrictErrors(exc);
-        Py_XDECREF(exc);
+        Py_DECREF(exc);
     }
     return NULL;
 }