commit - d4efa91b5a0b6d8d90ff1f847518ff59c17682e3
commit + 562580bce8d701d318471fe7601bc614a00c94ef
blob - 4b74c056672711e1ebae75fd3d7c79da18c35d82
blob + 2cffd8930319c67ebe5df79af4777c16a6e6b836
--- got/got.c
+++ got/got.c
@@ -2253,7 +2253,8 @@ match_object_id(struct got_object_id **id, char **labe
 			}
 			got_object_tag_close(tag);
 			return err;
-		} else if (err->code != GOT_ERR_NO_OBJ)
+		} else if (err->code != GOT_ERR_OBJ_TYPE &&
+		    err->code != GOT_ERR_NO_OBJ)
 			return err;
 	}
 
blob - 43a0f3a840e30d3749f4690d900e34f9cc447465
blob + 5df3441a4dead2afbdacad91ebb4e819f7814a6d
--- regress/cmdline/diff.sh
+++ regress/cmdline/diff.sh
@@ -195,7 +195,68 @@ function test_diff_tag {
 	local commit_id2=`git_show_head $testroot/repo`
 
 	(cd $testroot/repo && git tag -m "test" $tag2)
+
+	echo "diff $commit_id0 refs/tags/$tag1" > $testroot/stdout.expected
+	echo -n 'blob - ' >> $testroot/stdout.expected
+	got tree -r $testroot/repo -c $commit_id0 -i | grep 'alpha$' | \
+		cut -d' ' -f 1 >> $testroot/stdout.expected
+	echo -n 'blob + ' >> $testroot/stdout.expected
+	got tree -r $testroot/repo -i | grep 'alpha$' | cut -d' ' -f 1 \
+		>> $testroot/stdout.expected
+	echo '--- alpha' >> $testroot/stdout.expected
+	echo '+++ alpha' >> $testroot/stdout.expected
+	echo '@@ -1 +1 @@' >> $testroot/stdout.expected
+	echo '-alpha' >> $testroot/stdout.expected
+	echo '+modified alpha' >> $testroot/stdout.expected
+
+	got diff -r $testroot/repo $commit_id0 $tag1 > $testroot/stdout
+	cmp -s $testroot/stdout.expected $testroot/stdout
+	ret="$?"
+	if [ "$ret" != "0" ]; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	echo "diff refs/tags/$tag1 refs/tags/$tag2" > $testroot/stdout.expected
+	echo "blob - /dev/null" >> $testroot/stdout.expected
+	echo -n 'blob + ' >> $testroot/stdout.expected
+	got tree -r $testroot/repo -i -c $commit_id2 | grep 'new$' | \
+		cut -d' ' -f 1 | tr -d '\n' >> $testroot/stdout.expected
+	echo " (mode 644)" >> $testroot/stdout.expected
+	echo '--- /dev/null' >> $testroot/stdout.expected
+	echo '+++ new' >> $testroot/stdout.expected
+	echo '@@ -0,0 +1 @@' >> $testroot/stdout.expected
+	echo '+new file' >> $testroot/stdout.expected
 
+	got diff -r $testroot/repo $tag1 $tag2 > $testroot/stdout
+	cmp -s $testroot/stdout.expected $testroot/stdout
+	ret="$?"
+	if [ "$ret" != "0" ]; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+	fi
+	test_done "$testroot" "$ret"
+}
+
+function test_diff_lightweight_tag {
+	local testroot=`test_init diff_tag`
+	local commit_id0=`git_show_head $testroot/repo`
+	local tag1=1.0.0
+	local tag2=2.0.0
+
+	echo "modified alpha" > $testroot/repo/alpha
+	git_commit $testroot/repo -m "changed alpha"
+	local commit_id1=`git_show_head $testroot/repo`
+
+	(cd $testroot/repo && git tag $tag1)
+
+	echo "new file" > $testroot/repo/new
+	(cd $testroot/repo && git add new)
+	git_commit $testroot/repo -m "new file"
+	local commit_id2=`git_show_head $testroot/repo`
+
+	(cd $testroot/repo && git tag $tag2)
+
 	echo "diff $commit_id0 refs/tags/$tag1" > $testroot/stdout.expected
 	echo -n 'blob - ' >> $testroot/stdout.expected
 	got tree -r $testroot/repo -c $commit_id0 -i | grep 'alpha$' | \
@@ -270,4 +331,5 @@ function test_diff_ignore_whitespace {
 run_test test_diff_basic
 run_test test_diff_shows_conflict
 run_test test_diff_tag
+run_test test_diff_lightweight_tag
 run_test test_diff_ignore_whitespace