--- a/src/py_adonthell_wrap.cc	2014-10-20 14:21:57.495642785 +0200
+++ b/src/py_adonthell_wrap.cc	2014-10-20 14:22:35.019293237 +0200
@@ -867,7 +867,7 @@
     Py_DECREF(old_str);
     Py_DECREF(value);
   } else {
-    PyErr_Format(PyExc_RuntimeError, mesg);
+    PyErr_Format(PyExc_RuntimeError, "%s", mesg);
   }
 }