Renamed PyString to PyBytes
diff --git a/Objects/stringlib/string_format.h b/Objects/stringlib/string_format.h
index be8e8080..2e9c7ef 100644
--- a/Objects/stringlib/string_format.h
+++ b/Objects/stringlib/string_format.h
@@ -496,7 +496,7 @@
 #if PY_VERSION_HEX >= 0x03000000
     assert(PyUnicode_Check(result));
 #else
-    assert(PyString_Check(result) || PyUnicode_Check(result));
+    assert(PyBytes_Check(result) || PyUnicode_Check(result));
 
     /* Convert result to our type.  We could be str, and result could
        be unicode */