1 files changed, 10 insertions, 1 deletions
diff --git a/Lib/pdb.py b/Lib/pdb.py
index 57a2b45..29746d7 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -1193,7 +1193,16 @@ def set_trace():
 
 # Post-Mortem interface
 
-def post_mortem(t):
+def post_mortem(t=None):
+    # handling the default
+    if t is None:
+        # sys.exc_info() returns (type, value, traceback) if an exception is
+        # being handled, otherwise it returns None
+        t = sys.exc_info()[2]
+        if t is None:
+            raise ValueError("A valid traceback must be passed if no "
+                                               "exception is being handled")
+
     p = Pdb()
     p.reset()
     while t.tb_next is not None: