diff --git a/ref-filter.c b/ref-filter.c
index ba85869755..8ba0e31915 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -345,9 +345,11 @@ static int contents_atom_parser(const struct ref_format *format, struct used_ato
 		atom->u.contents.option = C_SIG;
 	else if (!strcmp(arg, "subject"))
 		atom->u.contents.option = C_SUB;
-	else if (skip_prefix(arg, "trailers", &arg)) {
-		skip_prefix(arg, ":", &arg);
-		if (trailers_atom_parser(format, atom, *arg ? arg : NULL, err))
+	else if (!strcmp(arg, "trailers")) {
+		if (trailers_atom_parser(format, atom, NULL, err))
+			return -1;
+	} else if (skip_prefix(arg, "trailers:", &arg)) {
+		if (trailers_atom_parser(format, atom, arg, err))
 			return -1;
 	} else if (skip_prefix(arg, "lines=", &arg)) {
 		atom->u.contents.option = C_LINES;
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index a83579fbdf..58adee7d18 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -776,61 +776,40 @@ test_expect_success 'set up trailers for next test' '
 '
 
 test_expect_success '%(trailers:unfold) unfolds trailers' '
-	git for-each-ref --format="%(trailers:unfold)" refs/heads/master >actual &&
 	{
 		unfold <trailers
 		echo
 	} >expect &&
+	git for-each-ref --format="%(trailers:unfold)" refs/heads/master >actual &&
+	test_cmp expect actual &&
+	git for-each-ref --format="%(contents:trailers:unfold)" refs/heads/master >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success '%(trailers:only) shows only "key: value" trailers' '
-	git for-each-ref --format="%(trailers:only)" refs/heads/master >actual &&
 	{
 		grep -v patch.description <trailers &&
 		echo
 	} >expect &&
+	git for-each-ref --format="%(trailers:only)" refs/heads/master >actual &&
+	test_cmp expect actual &&
+	git for-each-ref --format="%(contents:trailers:only)" refs/heads/master >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success '%(trailers:only) and %(trailers:unfold) work together' '
+	{
+		grep -v patch.description <trailers | unfold &&
+		echo
+	} >expect &&
 	git for-each-ref --format="%(trailers:only,unfold)" refs/heads/master >actual &&
-	git for-each-ref --format="%(trailers:unfold,only)" refs/heads/master >reverse &&
-	test_cmp actual reverse &&
-	{
-		grep -v patch.description <trailers | unfold &&
-		echo
-	} >expect &&
-	test_cmp expect actual
-'
-
-test_expect_success '%(contents:trailers:unfold) unfolds trailers' '
-	git for-each-ref --format="%(contents:trailers:unfold)" refs/heads/master >actual &&
-	{
-		unfold <trailers
-		echo
-	} >expect &&
-	test_cmp expect actual
-'
-
-test_expect_success '%(contents:trailers:only) shows only "key: value" trailers' '
-	git for-each-ref --format="%(contents:trailers:only)" refs/heads/master >actual &&
-	{
-		grep -v patch.description <trailers &&
-		echo
-	} >expect &&
-	test_cmp expect actual
-'
-
-test_expect_success '%(contents:trailers:only) and %(contents:trailers:unfold) work together' '
+	test_cmp expect actual &&
+	git for-each-ref --format="%(trailers:unfold,only)" refs/heads/master >actual &&
+	test_cmp actual actual &&
 	git for-each-ref --format="%(contents:trailers:only,unfold)" refs/heads/master >actual &&
-	git for-each-ref --format="%(contents:trailers:unfold,only)" refs/heads/master >reverse &&
-	test_cmp actual reverse &&
-	{
-		grep -v patch.description <trailers | unfold &&
-		echo
-	} >expect &&
-	test_cmp expect actual
+	test_cmp expect actual &&
+	git for-each-ref --format="%(contents:trailers:unfold,only)" refs/heads/master >actual &&
+	test_cmp actual actual
 '
 
 test_expect_success '%(trailers) rejects unknown trailers arguments' '
@@ -839,15 +818,16 @@ test_expect_success '%(trailers) rejects unknown trailers arguments' '
 	fatal: unknown %(trailers) argument: unsupported
 	EOF
 	test_must_fail git for-each-ref --format="%(trailers:unsupported)" 2>actual &&
+	test_i18ncmp expect actual &&
+	test_must_fail git for-each-ref --format="%(contents:trailers:unsupported)" 2>actual &&
 	test_i18ncmp expect actual
 '
 
-test_expect_success '%(contents:trailers) rejects unknown trailers arguments' '
-	# error message cannot be checked under i18n
+test_expect_success 'if arguments, %(contents:trailers) shows error if colon is missing' '
 	cat >expect <<-EOF &&
-	fatal: unknown %(trailers) argument: unsupported
+	fatal: unrecognized %(contents) argument: trailersonly
 	EOF
-	test_must_fail git for-each-ref --format="%(contents:trailers:unsupported)" 2>actual &&
+	test_must_fail git for-each-ref --format="%(contents:trailersonly)" 2>actual &&
 	test_i18ncmp expect actual
 '