diff --git a/core/bytes/bytes.odin b/core/bytes/bytes.odin
index 5a510951e..45eb44307 100644
--- a/core/bytes/bytes.odin
+++ b/core/bytes/bytes.odin
@@ -476,11 +476,9 @@ last_index_byte :: proc(s: []byte, c: byte) -> int #no_bounds_check {
 	// worth vectorizing assuming there is a hardware vector unit, and
 	// the data size is large enough.
 	if i < SIMD_REG_SIZE_128 {
-		if i > 0 { // Handle s == nil.
-			for /**/; i >= 0; i -= 1 {
-				if s[i] == c {
-					return i
-				}
+		#reverse for ch, j in s {
+			if ch == c {
+				return j
 			}
 		}
 		return -1
diff --git a/tests/core/bytes/test_core_bytes.odin b/tests/core/bytes/test_core_bytes.odin
index fb3c460aa..7f078c423 100644
--- a/tests/core/bytes/test_core_bytes.odin
+++ b/tests/core/bytes/test_core_bytes.odin
@@ -87,3 +87,11 @@ test_index_byte_zero :: proc(t: ^testing.T) {
 		}
 	}
 }
+
+@test
+test_last_index_byte_bounds :: proc(t: ^testing.T) {
+	input := "helloworld.odin."
+	assert(len(input) == 16)
+	idx := bytes.last_index_byte(transmute([]byte)(input[:len(input)-1]), '.')
+	testing.expect_value(t, idx, 10)
+}
\ No newline at end of file