diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -1434,6 +1434,7 @@
     s = bytes(range(256))
     for i in range(256):
         s[i:i+1]
+        x = chr(i)
 
 def findtestdir(path=None):
     return path or os.path.dirname(__file__) or os.curdir