diff --git a/Lib/functools.py b/Lib/functools.py
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -67,7 +67,9 @@ def total_ordering(cls):
                    ('__lt__', lambda self, other: not self >= other)]
     }
     roots = set(dir(cls)) & set(convert)
-    assert roots, 'must define at least one ordering operation: < > <= >='
+    if not roots:
+        raise TypeError('must define at least one ordering operation:'
+                        '__lt__, __le__, __gt__ or __ge__ ')
     root = max(roots)       # prefer __lt __ to __le__ to __gt__ to __ge__
     for opname, opfunc in convert[root]:
         if opname not in roots: