diff --git a/Lib/test/test_mutants.py b/Lib/test/test_mutants.py
index 60a17aa8e53..d495704c688 100644
--- a/Lib/test/test_mutants.py
+++ b/Lib/test/test_mutants.py
@@ -69,14 +69,12 @@ def maybe_mutate():
 
     elif keys:
         # Delete a key at random.
+        mutate = 0   # disable mutation until key deleted
         i = random.randrange(len(keys))
         key = keys[i]
         del target[key]
-        # CAUTION:  don't use keys.remove(key) here.  Or do <wink>.  The
-        # point is that .remove() would trigger more comparisons, and so
-        # also more calls to this routine.  We're mutating often enough
-        # without that.
         del keys[i]
+        mutate = 1
 
 # A horrid class that triggers random mutations of dict1 and dict2 when
 # instances are compared.