Index: Lib/test/test_descr.py
===================================================================
--- Lib/test/test_descr.py	(revision 3142)
+++ Lib/test/test_descr.py	(working copy)
@@ -479,6 +479,18 @@
         pass
     else:
         raise TestFailed, "should have raised OverflowError"
+    try:
+        foo = int(None)
+    except TypeError:
+        pass
+    else:
+        raise TestFailed, "should have raised TypeError"
+    try:
+        foo = C(None)
+    except TypeError:
+        pass
+    else:
+        raise TestFailed, "should have raised TypeError"
 
 def longs():
     if verbose: print "Testing long operations..."
Index: src/org/python/core/PyInteger.java
===================================================================
--- src/org/python/core/PyInteger.java	(revision 3142)
+++ src/org/python/core/PyInteger.java	(working copy)
@@ -687,7 +687,14 @@
             	if (x instanceof PyBoolean) {
             		return (coerce(x) == 0) ? Py.Zero : Py.One;
             	}
-                return x.__int__();
+                try {
+                    return x.__int__();
+                }
+                catch (PyException pye) {
+                    if (!Py.matchException(pye, Py.AttributeError))
+                        throw pye;
+                    throw Py.TypeError("int() argument must be a string or a number");
+                }
             }
             if (!(x instanceof PyString)) {
                 throw Py
@@ -699,7 +706,15 @@
                 return new PyIntegerDerived(subtype, 0);
             }
             if (base == -909) {
-                PyObject intOrLong = x.__int__();
+                PyObject intOrLong;
+                try {
+                    intOrLong = x.__int__();
+                }
+                catch (PyException pye) {
+                    if (!Py.matchException(pye, Py.AttributeError))
+                        throw pye;
+                    throw Py.TypeError("int() argument must be a string or a number");
+                }
                 if (intOrLong instanceof PyInteger) {
                     return new PyIntegerDerived(subtype, ((PyInteger)intOrLong).getValue());
                 }