diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -1335,6 +1335,9 @@
         env['TESTTMP'] = _bytes2sys(self._testtmp)
         env['TESTNAME'] = self.name
         env['HOME'] = _bytes2sys(self._testtmp)
+        if os.name == 'nt':
+            # py3.8+ ignores HOME: https://bugs.python.org/issue36264
+            env['USERPROFILE'] = env['HOME']
         formated_timeout = _bytes2sys(b"%d" % default_defaults['timeout'][1])
         env['HGTEST_TIMEOUT_DEFAULT'] = formated_timeout
         env['HGTEST_TIMEOUT'] = _bytes2sys(b"%d" % self._timeout)
diff --git a/tests/test-template-map.t b/tests/test-template-map.t
--- a/tests/test-template-map.t
+++ b/tests/test-template-map.t
@@ -1972,6 +1972,7 @@
   > EOF
 
   $ HOME=`pwd`/home; export HOME
+  $ USERPROFILE=`pwd`/home; export USERPROFILE
 
   $ cat > latesttag/.hg/hgrc <<EOF
   > [ui]