diff --git a/log-tree.c b/log-tree.c
index 1e56df6..f02343a 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -514,7 +514,7 @@
 			    "merged tag '%s'\n", tag->tag);
 	else if ((nth = which_parent(&tag->tagged->oid, commit)) < 0)
 		strbuf_addf(&verify_message, "tag %s names a non-parent %s\n",
-				    tag->tag, tag->tagged->oid.hash);
+				    tag->tag, oid_to_hex(&tag->tagged->oid));
 	else
 		strbuf_addf(&verify_message,
 			    "parent #%d, tagged '%s'\n", nth + 1, tag->tag);
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 819c24d..eecac18 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -1596,6 +1596,26 @@
 	grep "^| | gpg: Good signature" actual
 '
 
+test_expect_success GPG 'log --graph --show-signature for merged tag in shallow clone' '
+	test_when_finished "git reset --hard && git checkout master" &&
+	git checkout -b plain-shallow master &&
+	echo aaa >bar &&
+	git add bar &&
+	git commit -m bar_commit &&
+	git checkout --detach master &&
+	echo bbb >baz &&
+	git add baz &&
+	git commit -m baz_commit &&
+	git tag -s -m signed_tag_msg signed_tag_shallow &&
+	hash=$(git rev-parse HEAD) &&
+	git checkout plain-shallow &&
+	git merge --no-ff -m msg signed_tag_shallow &&
+	git clone --depth 1 --no-local . shallow &&
+	test_when_finished "rm -rf shallow" &&
+	git -C shallow log --graph --show-signature -n1 plain-shallow >actual &&
+	grep "tag signed_tag_shallow names a non-parent $hash" actual
+'
+
 test_expect_success GPGSM 'log --graph --show-signature for merged tag x509' '
 	test_when_finished "git reset --hard && git checkout master" &&
 	test_config gpg.format x509 &&