diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index 33d83a6..33c302d 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -91,7 +91,6 @@
     """
     exits = []
     vars = []
-    exc = (None, None, None)
     try:
         try:
             for context in contexts:
@@ -103,6 +102,8 @@
             yield vars
         except:
             exc = sys.exc_info()
+        else:
+            exc = (None, None, None)
     finally:
         while exits:
             exit = exits.pop()
@@ -110,6 +111,8 @@
                 exit(*exc)
             except:
                 exc = sys.exc_info()
+            else:
+                exc = (None, None, None)
         if exc != (None, None, None):
             raise