diff --git a/Python/_warnings.c b/Python/_warnings.c
index d03b452..12b1021 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -378,15 +378,47 @@
             show_warning(filename, lineno, text, category, sourceline);
         }
         else {
-            PyObject *res;
-            
-            res = PyObject_CallFunctionObjArgs(show_fxn, message, category,
+            const char *msg = "functions overriding warnings.showwarning() "
+                                "must support the 'line' argument";
+            const char *text_char = PyUnicode_AsString(text);
+
+            if (strcmp(msg, text_char) == 0) {
+                /* Prevent infinite recursion by using built-in implementation
+                   of showwarning(). */
+                show_warning(filename, lineno, text, category, sourceline);
+            }
+            else {
+                PyObject *check_fxn;
+                PyObject *defaults;
+                PyObject *res;
+
+                if (PyMethod_Check(show_fxn))
+                    check_fxn = PyMethod_Function(show_fxn);
+                else if (PyFunction_Check(show_fxn))
+                    check_fxn = show_fxn;
+                else {
+                    PyErr_SetString(PyExc_TypeError,
+                                    "warnings.showwarning() must be set to a "
+                                    "function or method");
+                    Py_DECREF(show_fxn);
+                    goto cleanup;
+                }
+
+                defaults = PyFunction_GetDefaults(check_fxn);
+                /* A proper implementation of warnings.showwarning() should
+                    have at least two default arguments. */
+                if ((defaults == NULL) || (PyTuple_Size(defaults) < 2)) {
+                    if (PyErr_WarnEx(PyExc_DeprecationWarning, msg, 1) < 0)
+                        goto cleanup;
+                }
+                res = PyObject_CallFunctionObjArgs(show_fxn, message, category,
                                                     filename, lineno_obj,
                                                     NULL);
-            Py_DECREF(show_fxn);
-            Py_XDECREF(res);
-            if (res == NULL)
-                goto cleanup;
+                Py_DECREF(show_fxn);
+                Py_XDECREF(res);
+                if (res == NULL)
+                    goto cleanup;
+            }
         }
     }
     else /* if (rc == -1) */
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index e2ba185..7712518 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -83,6 +83,7 @@
 int Py_UseClassExceptionsFlag = 1; /* Needed by bltinmodule.c: deprecated */
 int Py_FrozenFlag; /* Needed by getpath.c */
 int Py_IgnoreEnvironmentFlag; /* e.g. PYTHONPATH, PYTHONHOME */
+int Py_NoUserSiteDirectory = 0; /* for -s and site.py */
 
 /* PyModule_GetWarningsModule is no longer necessary as of 2.6
 since _warnings is builtin.  This API should not be used. */
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index ec167f0..c33457f 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1097,7 +1097,7 @@
 	{"interactive",		"-i"},
 	{"optimize",		"-O or -OO"},
 	{"dont_write_bytecode",	"-B"},
-	/* {"no_user_site",	"-s"}, */
+	{"no_user_site",	"-s"},
 	{"no_site",		"-S"},
 	{"ignore_environment",	"-E"},
 	{"tabcheck",		"-t or -tt"},
@@ -1116,9 +1116,9 @@
 	flags__doc__,	/* doc */
 	flags_fields,	/* fields */
 #ifdef RISCOS
-	11
+	12
 #else
-	10
+	11
 #endif
 };
 
@@ -1141,7 +1141,7 @@
 	SetFlag(Py_InteractiveFlag);
 	SetFlag(Py_OptimizeFlag);
 	SetFlag(Py_DontWriteBytecodeFlag);
-	/* SetFlag(Py_NoUserSiteDirectory); */
+	SetFlag(Py_NoUserSiteDirectory);
 	SetFlag(Py_NoSiteFlag);
 	SetFlag(Py_IgnoreEnvironmentFlag);
 	SetFlag(Py_TabcheckFlag);