diff --git a/refs/files-backend.c b/refs/files-backend.c
index 64f51f0da905a9..3b28d1b4fda3fd 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1890,7 +1890,10 @@ static int files_log_ref_write(struct files_ref_store *refs,
 	if (logfd < 0)
 		return 0;
 	result = log_ref_write_fd(logfd, old_oid, new_oid,
-				  git_committer_info(0), msg);
+				  fmt_ident(getenv("GIT_COMMITTER_NAME"),
+					    getenv("GIT_COMMITTER_EMAIL"),
+					    WANT_COMMITTER_IDENT, NULL, 0),
+				  msg);
 	if (result) {
 		struct strbuf sb = STRBUF_INIT;
 		int save_errno = errno;
diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index e2316f1dd4c200..b3f03be5595b4f 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -272,19 +272,19 @@ test_expect_success "clean up reflog" '
 
 test_expect_success "create $m (logged by touch)" '
 	test_config core.logAllRefUpdates false &&
-	GIT_COMMITTER_DATE="2005-05-26 23:30" \
+	GIT_TEST_DATE_NOW=1117150200 \
 	git update-ref --create-reflog HEAD $A -m "Initial Creation" &&
 	test $A = $(git show-ref -s --verify $m)
 '
 test_expect_success "update $m (logged by touch)" '
 	test_config core.logAllRefUpdates false &&
-	GIT_COMMITTER_DATE="2005-05-26 23:31" \
+	GIT_TEST_DATE_NOW=1117150260 \
 	git update-ref HEAD $B $A -m "Switch" &&
 	test $B = $(git show-ref -s --verify $m)
 '
 test_expect_success "set $m (logged by touch)" '
 	test_config core.logAllRefUpdates false &&
-	GIT_COMMITTER_DATE="2005-05-26 23:41" \
+	GIT_TEST_DATE_NOW=1117150860 \
 	git update-ref HEAD $A &&
 	test $A = $(git show-ref -s --verify $m)
 '
@@ -302,19 +302,19 @@ test_expect_success "verifying $m's log (logged by touch)" '
 
 test_expect_success "create $m (logged by config)" '
 	test_config core.logAllRefUpdates true &&
-	GIT_COMMITTER_DATE="2005-05-26 23:32" \
+	GIT_TEST_DATE_NOW=1117150320 \
 	git update-ref HEAD $A -m "Initial Creation" &&
 	test $A = $(git show-ref -s --verify $m)
 '
 test_expect_success "update $m (logged by config)" '
 	test_config core.logAllRefUpdates true &&
-	GIT_COMMITTER_DATE="2005-05-26 23:33" \
+	GIT_TEST_DATE_NOW=1117150380 \
 	git update-ref HEAD $B $A -m "Switch" &&
 	test $B = $(git show-ref -s --verify $m)
 '
 test_expect_success "set $m (logged by config)" '
 	test_config core.logAllRefUpdates true &&
-	GIT_COMMITTER_DATE="2005-05-26 23:43" \
+	GIT_TEST_DATE_NOW=1117150980 \
 	git update-ref HEAD $A &&
 	test $A = $(git show-ref -s --verify $m)
 '
@@ -445,24 +445,24 @@ test_expect_success 'query reflog with gap' '
 
 test_expect_success 'creating initial files' '
 	test_when_finished rm -f M &&
+	test_tick &&
 	echo TEST >F &&
 	git add F &&
-	GIT_AUTHOR_DATE="2005-05-26 23:30" \
-	GIT_COMMITTER_DATE="2005-05-26 23:30" git commit -m add -a &&
+	GIT_TEST_DATE_NOW=1117150200 git commit -m add -a &&
+	test_tick &&
 	h_TEST=$(git rev-parse --verify HEAD) &&
 	echo The other day this did not work. >M &&
 	echo And then Bob told me how to fix it. >>M &&
 	echo OTHER >F &&
-	GIT_AUTHOR_DATE="2005-05-26 23:41" \
-	GIT_COMMITTER_DATE="2005-05-26 23:41" git commit -F M -a &&
+	GIT_TEST_DATE_NOW=1117150860 git commit -F M -a &&
+	test_tick &&
 	h_OTHER=$(git rev-parse --verify HEAD) &&
-	GIT_AUTHOR_DATE="2005-05-26 23:44" \
-	GIT_COMMITTER_DATE="2005-05-26 23:44" git commit --amend &&
+	GIT_TEST_DATE_NOW=1117151040 git commit --amend &&
+	test_tick &&
 	h_FIXED=$(git rev-parse --verify HEAD) &&
 	echo Merged initial commit and a later commit. >M &&
 	echo $h_TEST >.git/MERGE_HEAD &&
-	GIT_AUTHOR_DATE="2005-05-26 23:45" \
-	GIT_COMMITTER_DATE="2005-05-26 23:45" git commit -F M &&
+	GIT_TEST_DATE_NOW=1117151100 git commit -F M &&
 	h_MERGED=$(git rev-parse --verify HEAD)
 '
 
diff --git a/t/t1411-reflog-show.sh b/t/t1411-reflog-show.sh
index 975c4ea83a877b..c8fb45423657f8 100755
--- a/t/t1411-reflog-show.sh
+++ b/t/t1411-reflog-show.sh
@@ -7,10 +7,7 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 . ./test-lib.sh
 
 test_expect_success 'setup' '
-	echo content >file &&
-	git add file &&
-	test_tick &&
-	git commit -m one
+	test_commit one file content
 '
 
 commit=$(git rev-parse --short HEAD)
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 78e054ab503a65..35aa16663ea395 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -397,21 +397,24 @@ test_commit () {
 	then
 		test_tick
 	fi &&
-	git ${indir:+ -C "$indir"} commit \
+	GIT_TEST_DATE_NOW=$test_tick TZ=PDT+7 \
+	    git ${indir:+ -C "$indir"} commit \
 	    ${author:+ --author "$author"} \
 	    $signoff -m "$1" &&
 	case "$tag" in
 	none)
 		;;
 	light)
-		git ${indir:+ -C "$indir"} tag "${4:-$1}"
+		GIT_TEST_DATE_NOW=$test_tick TZ=PDT+7 \
+			git ${indir:+ -C "$indir"} tag "${4:-$1}"
 		;;
 	annotate)
 		if test -z "$notick"
 		then
 			test_tick
 		fi &&
-		git ${indir:+ -C "$indir"} tag -a -m "$1" "${4:-$1}"
+		GIT_TEST_DATE_NOW=$test_tick TZ=PDT+7 \
+			git ${indir:+ -C "$indir"} tag -a -m "$1" "${4:-$1}"
 		;;
 	esac
 }