diff --git a/builtin/blame.c b/builtin/blame.c
index d7630ac89c..7555c445ab 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -489,9 +489,9 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 			fputs(color, stdout);
 
 		if (suspect->commit->object.flags & UNINTERESTING) {
-			if (blank_boundary)
-				memset(hex, ' ', length);
-			else if (!(opt & OUTPUT_ANNOTATE_COMPAT)) {
+			if (blank_boundary) {
+				memset(hex, ' ', strlen(hex));
+			} else if (!(opt & OUTPUT_ANNOTATE_COMPAT)) {
 				length--;
 				putchar('^');
 			}
diff --git a/t/t8002-blame.sh b/t/t8002-blame.sh
index b3f8b63d2e..1ad039e123 100755
--- a/t/t8002-blame.sh
+++ b/t/t8002-blame.sh
@@ -134,6 +134,24 @@ test_expect_success 'blame --abbrev gets truncated with boundary commit' '
 	check_abbrev $hexsz --abbrev=9000 ^HEAD
 '
 
+test_expect_success 'blame --abbrev -b truncates the blank boundary' '
+	# Note that `--abbrev=` always gets incremented by 1, which is why we
+	# expect 11 leading spaces and not 10.
+	cat >expect <<-EOF &&
+	$(printf "%0.s " $(test_seq 11)) (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
+	EOF
+	git blame -b --abbrev=10 ^HEAD -- abbrev.t >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'blame with excessive --abbrev and -b culls to hash length' '
+	cat >expect <<-EOF &&
+	$(printf "%0.s " $(test_seq $hexsz)) (<author@example.com> 2005-04-07 15:45:13 -0700 1) abbrev
+	EOF
+	git blame -b --abbrev=9000 ^HEAD -- abbrev.t >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success '--exclude-promisor-objects does not BUG-crash' '
 	test_must_fail git blame --exclude-promisor-objects one
 '