diff --git a/mercurial/help.py b/mercurial/help.py
--- a/mercurial/help.py
+++ b/mercurial/help.py
@@ -338,7 +338,7 @@
             aliases, entry = cmdutil.findcmd(name, commands.table,
                                              strict=unknowncmd)
         except error.AmbiguousCommand as inst:
-            # py3k fix: except vars can't be used outside the scope of the
+            # py3 fix: except vars can't be used outside the scope of the
             # except block, nor can be used inside a lambda. python issue4617
             prefix = inst.args[0]
             select = lambda c: cmdutil.parsealiases(c)[0].startswith(prefix)
diff --git a/mercurial/thirdparty/zope/interface/_compat.py b/mercurial/thirdparty/zope/interface/_compat.py
--- a/mercurial/thirdparty/zope/interface/_compat.py
+++ b/mercurial/thirdparty/zope/interface/_compat.py
@@ -50,7 +50,7 @@
     PYTHON3 = True
     PYTHON2 = False
 
-def _skip_under_py3k(test_method):
+def _skip_under_py3(test_method):
     import unittest
     return unittest.skipIf(sys.version_info[0] >= 3, "Only on Python 2")(test_method)
 
diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -641,8 +641,8 @@
     # chg disables demandimport intentionally for performance wins.
     return ((not has_chg()) and os.environ.get('HGDEMANDIMPORT') != 'disable')
 
-@check("py3k", "running with Python 3.x")
-def has_py3k():
+@check("py3", "running with Python 3.x")
+def has_py3():
     return 3 == sys.version_info[0]
 
 @check("py3exe", "a Python 3.x interpreter is available")
diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -424,7 +424,7 @@
         help="prefer IPv6 to IPv4 for network related tests")
     hgconf.add_argument("--pure", action="store_true",
         help="use pure Python code instead of C extensions")
-    hgconf.add_argument("-3", "--py3k-warnings", action="store_true",
+    hgconf.add_argument("-3", "--py3-warnings", action="store_true",
         help="enable Py3k warnings on Python 2.7+")
     hgconf.add_argument("--with-chg", metavar="CHG",
         help="use specified chg wrapper in place of hg")
@@ -561,10 +561,10 @@
                 'warning: --slowtimeout option ignored with --debug\n')
         options.timeout = 0
         options.slowtimeout = 0
-    if options.py3k_warnings:
+    if options.py3_warnings:
         if PYTHON3:
             parser.error(
-                '--py3k-warnings can only be used on Python 2.7')
+                '--py3-warnings can only be used on Python 2.7')
 
     if options.blacklist:
         options.blacklist = parselistfiles(options.blacklist, 'blacklist')
@@ -688,7 +688,7 @@
                  first=False,
                  timeout=None,
                  startport=None, extraconfigopts=None,
-                 py3kwarnings=False, shell=None, hgcommand=None,
+                 py3warnings=False, shell=None, hgcommand=None,
                  slowtimeout=None, usechg=False,
                  useipv6=False):
         """Create a test from parameters.
@@ -717,7 +717,7 @@
         must have the form "key=value" (something understood by hgrc). Values
         of the form "foo.key=value" will result in "[foo] key=value".
 
-        py3kwarnings enables Py3k warnings.
+        py3warnings enables Py3k warnings.
 
         shell is the shell to execute tests in.
         """
@@ -743,7 +743,7 @@
         self._slowtimeout = slowtimeout
         self._startport = startport
         self._extraconfigopts = extraconfigopts or []
-        self._py3kwarnings = py3kwarnings
+        self._py3warnings = py3warnings
         self._shell = _bytespath(shell)
         self._hgcommand = hgcommand or b'hg'
         self._usechg = usechg
@@ -1217,8 +1217,8 @@
         return os.path.join(self._testdir, b'%s.out' % self.bname)
 
     def _run(self, env):
-        py3kswitch = self._py3kwarnings and b' -3' or b''
-        cmd = b'"%s"%s "%s"' % (PYTHON, py3kswitch, self.path)
+        py3switch = self._py3warnings and b' -3' or b''
+        cmd = b'%s%s "%s"' % (PYTHON, py3switch, self.path)
         vlog("# Running", cmd)
         normalizenewlines = os.name == 'nt'
         result = self._runcommand(cmd, env,
@@ -2891,7 +2891,7 @@
                     timeout=self.options.timeout,
                     startport=self._getport(count),
                     extraconfigopts=self.options.extra_config_opt,
-                    py3kwarnings=self.options.py3k_warnings,
+                    py3warnings=self.options.py3_warnings,
                     shell=self.options.shell,
                     hgcommand=self._hgcommand,
                     usechg=bool(self.options.with_chg or self.options.chg),
@@ -3023,7 +3023,7 @@
 
         self._usecorrectpython()
 
-        if self.options.py3k_warnings and not self.options.anycoverage:
+        if self.options.py3_warnings and not self.options.anycoverage:
             vlog("# Updating hg command to enable Py3k Warnings switch")
             with open(os.path.join(self._bindir, 'hg'), 'rb') as f:
                 lines = [line.rstrip() for line in f]
diff --git a/tests/test-check-py3-compat.t b/tests/test-check-py3-compat.t
--- a/tests/test-check-py3-compat.t
+++ b/tests/test-check-py3-compat.t
@@ -3,7 +3,7 @@
   $ . "$TESTDIR/helpers-testrepo.sh"
   $ cd "$TESTDIR"/..
 
-#if no-py3k
+#if no-py3
   $ testrepohg files 'set:(**.py)' \
   > -X hgdemandimport/demandimportpy2.py \
   > -X mercurial/thirdparty/cbor \
@@ -24,7 +24,7 @@
   setup.py not using absolute_import
 #endif
 
-#if py3k
+#if py3
   $ testrepohg files 'set:(**.py) - grep(pygments)' \
   > -X hgdemandimport/demandimportpy2.py \
   > -X hgext/fsmonitor/pywatchman \
@@ -41,7 +41,7 @@
   mercurial/scmposix.py: error importing: <ModuleNotFoundError> No module named 'fcntl' (error at scmposix.py:*) (windows !)
 #endif
 
-#if py3k pygments
+#if py3 pygments
   $ testrepohg files 'set:(**.py) and grep(pygments)' | sed 's|\\|/|g' \
   > | xargs "$PYTHON" contrib/check-py3-compat.py \
   > | sed 's/[0-9][0-9]*)$/*)/'
diff --git a/tests/test-debugcommands.t b/tests/test-debugcommands.t
--- a/tests/test-debugcommands.t
+++ b/tests/test-debugcommands.t
@@ -203,8 +203,8 @@
    {
     "chainid": 1,
     "chainlen": 1,
-    "chainratio": 1.02325581395, (no-py3k !)
-    "chainratio": 1.0232558139534884, (py3k !)
+    "chainratio": 1.02325581395, (no-py3 !)
+    "chainratio": 1.0232558139534884, (py3 !)
     "chainsize": 44,
     "compsize": 44,
     "deltatype": "base",
@@ -232,8 +232,8 @@
    {
     "chainid": 3,
     "chainlen": 1,
-    "chainratio": 1.02325581395, (no-py3k !)
-    "chainratio": 1.0232558139534884, (py3k !)
+    "chainratio": 1.02325581395, (no-py3 !)
+    "chainratio": 1.0232558139534884, (py3 !)
     "chainsize": 44,
     "compsize": 44,
     "deltatype": "base",
@@ -268,8 +268,8 @@
    {
     "chainid": 1,
     "chainlen": 1,
-    "chainratio": 1.02325581395, (no-py3k !)
-    "chainratio": 1.0232558139534884, (py3k !)
+    "chainratio": 1.02325581395, (no-py3 !)
+    "chainratio": 1.0232558139534884, (py3 !)
     "chainsize": 44,
     "compsize": 44,
     "deltatype": "base",
@@ -305,8 +305,8 @@
    {
     "chainid": 3,
     "chainlen": 1,
-    "chainratio": 1.02325581395, (no-py3k !)
-    "chainratio": 1.0232558139534884, (py3k !)
+    "chainratio": 1.02325581395, (no-py3 !)
+    "chainratio": 1.0232558139534884, (py3 !)
     "chainsize": 44,
     "compsize": 44,
     "deltatype": "base",
diff --git a/tests/test-extension.t b/tests/test-extension.t
--- a/tests/test-extension.t
+++ b/tests/test-extension.t
@@ -222,7 +222,7 @@
   ambigabs.s=libroot/ambig.py
   $TESTTMP/a
 
-#if no-py3k
+#if no-py3
   $ cat > $TESTTMP/libroot/mod/ambigrel.py <<NO_CHECK_EOF
   > from __future__ import print_function
   > import ambig # should load "libroot/mod/ambig.py"
@@ -290,7 +290,7 @@
   (extroot) import extroot.bar in func(): this is extroot.bar
   $TESTTMP/a
 
-#if no-py3k
+#if no-py3
   $ rm "$TESTTMP"/extroot/foo.*
   $ rm -Rf "$TESTTMP/extroot/__pycache__"
   $ cat > $TESTTMP/extroot/foo.py <<NO_CHECK_EOF
diff --git a/tests/test-globalopts.t b/tests/test-globalopts.t
--- a/tests/test-globalopts.t
+++ b/tests/test-globalopts.t
@@ -267,7 +267,7 @@
 #if no-chg
   $ hg --cwd c --config x --traceback id 2>&1 | grep -i 'traceback'
   Traceback (most recent call last):
-  Traceback (most recent call last): (py3k !)
+  Traceback (most recent call last): (py3 !)
 #else
 Traceback for '--config' errors not supported with chg.
   $ hg --cwd c --config x --traceback id 2>&1 | grep -i 'traceback'