Issue #21526: Skip test_booleans on Tcl < 8.5.
diff --git a/Lib/test/test_tcl.py b/Lib/test/test_tcl.py
index 8ff2ebf..927b0e3 100644
--- a/Lib/test/test_tcl.py
+++ b/Lib/test/test_tcl.py
@@ -406,6 +406,7 @@
         if tcl_version >= (8, 5):  # bignum was added in Tcl 8.5
             check('2**64', True)
 
+    @unittest.skipUnless(tcl_version >= (8, 5), 'requires Tcl version >= 8.5')
     def test_booleans(self):
         tcl = self.interp
         def check(expr, expected):