diff --git a/t/test-lib.sh b/t/test-lib.sh
index 2679a7596a..70668f5d31 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -449,6 +449,8 @@ unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
 unset XDG_CACHE_HOME
 unset XDG_CONFIG_HOME
 unset GITPERLLIB
+unset GIT_TRACE2_PARENT_NAME
+unset GIT_TRACE2_PARENT_SID
 TEST_AUTHOR_LOCALNAME=author
 TEST_AUTHOR_DOMAIN=example.com
 GIT_AUTHOR_EMAIL=${TEST_AUTHOR_LOCALNAME}@${TEST_AUTHOR_DOMAIN}