diff -r 41fd36f8f3ec Modules/nismodule.c
--- a/Modules/nismodule.c	Thu Aug 16 10:59:31 2012 +0200
+++ b/Modules/nismodule.c	Thu Aug 16 11:05:50 2012 +0200
@@ -44,12 +44,42 @@
 Returns an array of all available NIS maps within a domain. If domain\n\
 is not specified it defaults to the system default domain.\n");
 
-static PyObject *NisError;
+typedef struct {
+  PyObject *NisError;
+} nisstate;
+
+
+#define nis_state(o) ((nisstate *)PyModule_GetState(o))
+
+static int
+nis_clear(PyObject *m)
+{
+   Py_CLEAR(nis_state(m)->NisError);
+   return 0;
+}
+
+static int
+nis_traverse(PyObject *m, visitproc visit, void *arg)
+{
+    Py_VISIT(nis_state(m)->NisError);
+    return 0;
+}
+
+static void
+nis_free(void *m)
+{
+    nis_clear((PyObject *)m);
+}
+
+static PyModuleDef nismodule;
+
+#define nisstate_global ((nisstate *)PyModule_GetState(PyState_FindModule(&nismodule)))
+
 
 static PyObject *
 nis_error (int err)
 {
-    PyErr_SetString(NisError, yperr_string(err));
+    PyErr_SetString(nisstate_global->NisError, yperr_string(err));
     return NULL;
 }
 
@@ -367,12 +397,12 @@
         mapi++;
     }
     if (!server) {
-        PyErr_SetString(NisError, "No NIS master found for any map");
+        PyErr_SetString(nisstate_global->NisError, "No NIS master found for any map");
         return NULL;
     }
     cl = clnt_create(server, YPPROG, YPVERS, "tcp");
     if (cl == NULL) {
-        PyErr_SetString(NisError, clnt_spcreateerror(server));
+        PyErr_SetString(nisstate_global->NisError, clnt_spcreateerror(server));
         goto finally;
     }
     list = nisproc_maplist_2 (&dom, cl);
@@ -448,12 +478,12 @@
     PyModuleDef_HEAD_INIT,
     "nis",
     nis__doc__,
-    -1,
+    sizeof(nisstate),
     nis_methods,
     NULL,
-    NULL,
-    NULL,
-    NULL
+    nis_traverse,
+    nis_clear,
+    nis_free
 };
 
 PyObject*
@@ -464,8 +494,10 @@
     if (m == NULL)
         return NULL;
     d = PyModule_GetDict(m);
-    NisError = PyErr_NewException("nis.error", NULL, NULL);
-    if (NisError != NULL)
-        PyDict_SetItemString(d, "error", NisError);
+
+    nis_state(m)->NisError = PyErr_NewException("nis.error", NULL, NULL);
+    if (nis_state(m)->NisError != NULL)
+        PyDict_SetItemString(d, "error", nis_state(m)->NisError);
+
     return m;
 }