diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index 0c29e64..ccee961 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -584,6 +584,7 @@
         if chunksize <= 0:
             self._number_left = 0
             self._ready = True
+            del cache[self._job]
         else:
             self._number_left = length//chunksize + bool(length % chunksize)