diff -r de5a11836ad4 Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Sun Nov 22 12:30:54 2015 +0200
+++ b/Objects/unicodeobject.c	Sun Nov 22 11:37:19 2015 +0100
@@ -4984,7 +4984,7 @@
 
     /* Note: size will always be longer than the resulting Unicode
        character count */
-    if (PY_SSIZE_T_MAX / (Py_ssize_t)sizeof(wchar_t) < (size + 1))
+    if (PY_SSIZE_T_MAX / (Py_ssize_t)sizeof(wchar_t) < (unsigned long)(size + 1))
         return NULL;
     unicode = PyMem_RawMalloc((size + 1) * sizeof(wchar_t));
     if (!unicode)