diff -r 2914c826278e Modules/binascii.c
--- a/Modules/binascii.c	Thu Aug 16 10:19:01 2012 +0200
+++ b/Modules/binascii.c	Thu Aug 16 10:26:38 2012 +0200
@@ -60,8 +60,41 @@
 #include "zlib.h"
 #endif
 
-static PyObject *Error;
-static PyObject *Incomplete;
+typedef struct {
+  PyObject *Error;
+  PyObject *Incomplete;
+} binasciistate;
+
+
+#define binascii_state(o) ((binasciistate *)PyModule_GetState(o))
+
+static int
+binascii_clear(PyObject *m)
+{
+   Py_CLEAR(binascii_state(m)->Error);
+   Py_CLEAR(binascii_state(m)->Incomplete);
+   return 0;
+}
+
+static int
+binascii_traverse(PyObject *m, visitproc visit, void *arg)
+{
+    Py_VISIT(binascii_state(m)->Error);
+    Py_VISIT(binascii_state(m)->Incomplete);
+    return 0;
+}
+
+static void
+binascii_free(void *m)
+{
+    binascii_clear((PyObject *)m);
+}
+
+static PyModuleDef binasciimodule;
+
+#define binasciistate_global ((binasciistate *)PyModule_GetState(PyState_FindModule(&binasciimodule)))
+
+
 
 /*
 ** hqx lookup table, ascii->binary.
@@ -268,7 +301,7 @@
             ** '`' as zero instead of space.
             */
             if ( this_ch < ' ' || this_ch > (' ' + 64)) {
-                PyErr_SetString(Error, "Illegal char");
+                PyErr_SetString(binasciistate_global->Error, "Illegal char");
                 PyBuffer_Release(&pascii);
                 Py_DECREF(rv);
                 return NULL;
@@ -297,7 +330,7 @@
         /* Extra '`' may be written as padding in some cases */
         if ( this_ch != ' ' && this_ch != ' '+64 &&
              this_ch != '\n' && this_ch != '\r' ) {
-            PyErr_SetString(Error, "Trailing garbage");
+            PyErr_SetString(binasciistate_global->Error, "Trailing garbage");
             PyBuffer_Release(&pascii);
             Py_DECREF(rv);
             return NULL;
@@ -326,7 +359,7 @@
     bin_len = pbin.len;
     if ( bin_len > 45 ) {
         /* The 45 is a limit that appears in all uuencode's */
-        PyErr_SetString(Error, "At most 45 bytes at once");
+        PyErr_SetString(binasciistate_global->Error, "At most 45 bytes at once");
         PyBuffer_Release(&pbin);
         return NULL;
     }
@@ -480,7 +513,7 @@
 
     if (leftbits != 0) {
         PyBuffer_Release(&pascii);
-        PyErr_SetString(Error, "Incorrect padding");
+        PyErr_SetString(binasciistate_global->Error, "Incorrect padding");
         Py_DECREF(rv);
         return NULL;
     }
@@ -524,7 +557,7 @@
     assert(bin_len >= 0);
 
     if ( bin_len > BASE64_MAXBIN ) {
-        PyErr_SetString(Error, "Too much data for base64 line");
+        PyErr_SetString(binasciistate_global->Error, "Too much data for base64 line");
         PyBuffer_Release(&pbuf);
         return NULL;
     }
@@ -611,7 +644,7 @@
         if ( this_ch == SKIP )
             continue;
         if ( this_ch == FAIL ) {
-            PyErr_SetString(Error, "Illegal char");
+            PyErr_SetString(binasciistate_global->Error, "Illegal char");
             PyBuffer_Release(&pascii);
             Py_DECREF(rv);
             return NULL;
@@ -633,7 +666,7 @@
     }
 
     if ( leftbits && !done ) {
-        PyErr_SetString(Incomplete,
+        PyErr_SetString(binasciistate_global->Incomplete,
                         "String has incomplete number of bytes");
         PyBuffer_Release(&pascii);
         Py_DECREF(rv);
@@ -821,7 +854,7 @@
 #define INBYTE(b) \
     do { \
              if ( --in_len < 0 ) { \
-                       PyErr_SetString(Incomplete, ""); \
+                       PyErr_SetString(binasciistate_global->Incomplete, ""); \
                        Py_DECREF(rv); \
                        PyBuffer_Release(&pin); \
                        return NULL; \
@@ -855,7 +888,7 @@
             /* Note Error, not Incomplete (which is at the end
             ** of the string only). This is a programmer error.
             */
-            PyErr_SetString(Error, "Orphaned RLE code at start");
+            PyErr_SetString(binasciistate_global->Error, "Orphaned RLE code at start");
             PyBuffer_Release(&pin);
             Py_DECREF(rv);
             return NULL;
@@ -1170,7 +1203,7 @@
      */
     if (arglen % 2) {
         PyBuffer_Release(&parg);
-        PyErr_SetString(Error, "Odd-length string");
+        PyErr_SetString(binasciistate_global->Error, "Odd-length string");
         return NULL;
     }
 
@@ -1185,7 +1218,7 @@
         int top = to_int(Py_CHARMASK(argbuf[i]));
         int bot = to_int(Py_CHARMASK(argbuf[i+1]));
         if (top == -1 || bot == -1) {
-            PyErr_SetString(Error,
+            PyErr_SetString(binasciistate_global->Error,
                             "Non-hexadecimal digit found");
             goto finally;
         }
@@ -1546,12 +1579,12 @@
     PyModuleDef_HEAD_INIT,
     "binascii",
     doc_binascii,
-    -1,
+    sizeof(binasciistate),
     binascii_module_methods,
     NULL,
-    NULL,
-    NULL,
-    NULL
+    binascii_traverse,
+    binascii_clear,
+    binascii_free
 };
 
 PyMODINIT_FUNC
@@ -1566,10 +1599,10 @@
 
     d = PyModule_GetDict(m);
 
-    Error = PyErr_NewException("binascii.Error", PyExc_ValueError, NULL);
-    PyDict_SetItemString(d, "Error", Error);
-    Incomplete = PyErr_NewException("binascii.Incomplete", NULL, NULL);
-    PyDict_SetItemString(d, "Incomplete", Incomplete);
+    binascii_state(m)->Error = PyErr_NewException("binascii.Error", PyExc_ValueError, NULL);
+    PyDict_SetItemString(d, "Error", binascii_state(m)->Error);
+    binascii_state(m)->Incomplete = PyErr_NewException("binascii.Incomplete", NULL, NULL);
+    PyDict_SetItemString(d, "Incomplete", binascii_state(m)->Incomplete);
     if (PyErr_Occurred()) {
         Py_DECREF(m);
         m = NULL;