diff --git a/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_indexOf_Benchmark.scala b/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_indexOf_Benchmark.scala
index 4eab26438e..1b6c6d2a81 100644
--- a/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_indexOf_Benchmark.scala
+++ b/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_indexOf_Benchmark.scala
@@ -24,6 +24,8 @@ class ByteString_indexOf_Benchmark {
   val bss = start ++ start ++ start ++ start ++ start ++ ByteString("xyz")
 
   val bs = bss.compact // compacted
+  val oByte = 'o'.toByte
+  val zByte = 'z'.toByte
 
   /*
   original
@@ -46,10 +48,16 @@ class ByteString_indexOf_Benchmark {
   @Benchmark
   def bss_indexOf_from_far_index_case: Int = bss.indexOf('z', 109)
 
+  @Benchmark
+  def bss_indexOf_from_far_index_case_byte: Int = bss.indexOf(zByte, 109)
+
   @Benchmark
   def bss_indexOf_from_best_case: Int = bss.indexOf('a', 0)
 
   @Benchmark
-  def bs1_indexOf_from: Int = bs.indexOf('ö', 5)
+  def bs1_indexOf_from: Int = bs.indexOf('o', 5)
+
+  @Benchmark
+  def bs1_indexOf_from_byte: Int = bs.indexOf(oByte, 5)
 
 }
diff --git a/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_lastIndexOf_Benchmark.scala b/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_lastIndexOf_Benchmark.scala
new file mode 100644
index 0000000000..b809c0bf5b
--- /dev/null
+++ b/bench-jmh/src/main/scala/org/apache/pekko/util/ByteString_lastIndexOf_Benchmark.scala
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * license agreements; and to You under the Apache License, version 2.0:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * This file is part of the Apache Pekko project, which was derived from Akka.
+ */
+
+/*
+ * Copyright (C) 2014-2022 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package org.apache.pekko.util
+
+import java.util.concurrent.TimeUnit
+
+import org.openjdk.jmh.annotations._
+
+@State(Scope.Benchmark)
+@Measurement(timeUnit = TimeUnit.MILLISECONDS)
+class ByteString_lastIndexOf_Benchmark {
+  val start = ByteString("abcdefg") ++ ByteString("hijklmno") ++ ByteString("pqrstuv")
+  val bss = start ++ start ++ start ++ start ++ start ++ ByteString("xyz")
+
+  val bs = bss.compact // compacted
+  val bsLen = bs.length
+  val aByte = 'a'.toByte
+  val oByte = 'o'.toByte
+
+  @Benchmark
+  def bss_lastIndexOf_worst_case: Int = bss.lastIndexOf('a')
+
+  @Benchmark
+  def bss_lastIndexOf_far_index_case: Int = bss.lastIndexOf('a', 10)
+
+  @Benchmark
+  def bss_lastIndexOf_far_index_case_byte: Int = bss.lastIndexOf(aByte, 10)
+
+  @Benchmark
+  def bss_lastIndexOf_best_case: Int = bss.lastIndexOf('z')
+
+  @Benchmark
+  def bs1_lastIndexOf: Int = bs.lastIndexOf('o', bsLen - 5)
+
+  @Benchmark
+  def bs1_lastIndexOf_byte: Int = bs.lastIndexOf(oByte, bsLen - 5)
+
+}