diff --git a/builtin/blame.c b/builtin/blame.c
index 4916eb2bd2..e44a6bb30a 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1803,17 +1803,17 @@ static int prepare_lines(struct scoreboard *sb)
 static int read_ancestry(const char *graft_file)
 {
 	FILE *fp = fopen(graft_file, "r");
-	char buf[1024];
+	struct strbuf buf = STRBUF_INIT;
 	if (!fp)
 		return -1;
-	while (fgets(buf, sizeof(buf), fp)) {
+	while (!strbuf_getwholeline(&buf, fp, '\n')) {
 		/* The format is just "Commit Parent1 Parent2 ...\n" */
-		int len = strlen(buf);
-		struct commit_graft *graft = read_graft_line(buf, len);
+		struct commit_graft *graft = read_graft_line(buf.buf, buf.len);
 		if (graft)
 			register_commit_graft(graft, 0);
 	}
 	fclose(fp);
+	strbuf_release(&buf);
 	return 0;
 }
 
diff --git a/commit.c b/commit.c
index 5ff553872b..b9f9838110 100644
--- a/commit.c
+++ b/commit.c
@@ -196,19 +196,19 @@ struct commit_graft *read_graft_line(char *buf, int len)
 static int read_graft_file(const char *graft_file)
 {
 	FILE *fp = fopen(graft_file, "r");
-	char buf[1024];
+	struct strbuf buf = STRBUF_INIT;
 	if (!fp)
 		return -1;
-	while (fgets(buf, sizeof(buf), fp)) {
+	while (!strbuf_getwholeline(&buf, fp, '\n')) {
 		/* The format is just "Commit Parent1 Parent2 ...\n" */
-		int len = strlen(buf);
-		struct commit_graft *graft = read_graft_line(buf, len);
+		struct commit_graft *graft = read_graft_line(buf.buf, buf.len);
 		if (!graft)
 			continue;
 		if (register_commit_graft(graft, 1))
-			error("duplicate graft data: %s", buf);
+			error("duplicate graft data: %s", buf.buf);
 	}
 	fclose(fp);
+	strbuf_release(&buf);
 	return 0;
 }
 
diff --git a/t/annotate-tests.sh b/t/annotate-tests.sh
index c9d105d707..304c7b7d87 100644
--- a/t/annotate-tests.sh
+++ b/t/annotate-tests.sh
@@ -116,6 +116,27 @@ test_expect_success 'blame evil merge' '
 	check_count A 2 B 1 B1 2 B2 1 "A U Thor" 1
 '
 
+test_expect_success 'blame huge graft' '
+	test_when_finished "git checkout branch2" &&
+	test_when_finished "rm -f .git/info/grafts" &&
+	graft= &&
+	for i in 0 1 2
+	do
+		for j in 0 1 2 3 4 5 6 7 8 9
+		do
+			git checkout --orphan "$i$j" &&
+			printf "%s\n" "$i" "$j" >file &&
+			test_tick &&
+			GIT_AUTHOR_NAME=$i$j GIT_AUTHOR_EMAIL=$i$j@test.git \
+			git commit -a -m "$i$j" &&
+			commit=$(git rev-parse --verify HEAD) &&
+			graft="$graft$commit "
+		done
+	done &&
+	printf "%s " $graft >.git/info/grafts &&
+	check_count -h 00 01 1 10 1
+'
+
 test_expect_success 'setup incomplete line' '
 	echo "incomplete" | tr -d "\\012" >>file &&
 	GIT_AUTHOR_NAME="C" GIT_AUTHOR_EMAIL="C@test.git" \
diff --git a/t/t6101-rev-parse-parents.sh b/t/t6101-rev-parse-parents.sh
index 7ea14ced31..10b1452766 100755
--- a/t/t6101-rev-parse-parents.sh
+++ b/t/t6101-rev-parse-parents.sh
@@ -20,7 +20,17 @@ test_expect_success 'setup' '
 	test_commit start2 &&
 	git checkout master &&
 	git merge -m next start2 &&
-	test_commit final
+	test_commit final &&
+
+	test_seq 40 |
+	while read i
+	do
+		git checkout --orphan "b$i" &&
+		test_tick &&
+		git commit --allow-empty -m "$i" &&
+		commit=$(git rev-parse --verify HEAD) &&
+		printf "$commit " >>.git/info/grafts
+	done
 '
 
 test_expect_success 'start is valid' '
@@ -79,6 +89,10 @@ test_expect_success 'final^1^! = final^1 ^final^1^1 ^final^1^2' '
 	test_cmp expect actual
 '
 
+test_expect_success 'large graft octopus' '
+	test_cmp_rev_output b31 "git rev-parse --verify b1^30"
+'
+
 test_expect_success 'repack for next test' '
 	git repack -a -d
 '