diff --git a/py/magic/assertion.py b/py/magic/assertion.py
index 518fa06a3..31eb13c95 100644
--- a/py/magic/assertion.py
+++ b/py/magic/assertion.py
@@ -8,7 +8,14 @@ class AssertionError(BuiltinAssertionError):
     def __init__(self, *args):
         BuiltinAssertionError.__init__(self, *args)
         if args: 
-            self.msg = str(args[0])
+            try:
+                self.msg = str(args[0])
+            except (KeyboardInterrupt, SystemExit):
+                raise
+            except:
+                self.msg = "<[broken __repr__] %s at %0xd>" %(
+                    args[0].__class__, id(args[0]))
+            
         else: 
             f = sys._getframe(1)
             try:
diff --git a/py/magic/testing/test_assertion.py b/py/magic/testing/test_assertion.py
index d2eb0f8fd..b3b337175 100644
--- a/py/magic/testing/test_assertion.py
+++ b/py/magic/testing/test_assertion.py
@@ -96,3 +96,11 @@ def test_assert_implicit_multiline():
     except AssertionError, e:
         assert e.msg.find('assert [1, 2, 3] !=') != -1
 
+
+def test_assert_with_brokenrepr_arg():
+    class BrokenRepr:
+        def __repr__(self): 0 / 0
+    e = AssertionError(BrokenRepr())
+    if e.msg.find("broken __repr__") == -1:
+        py.test.fail("broken __repr__ not handle correctly")
+