diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index f58939f1b0a..abd8a68ce5f 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -2591,6 +2591,7 @@ public static int indexOf(final CharSequence seq, final CharSequence searchSeq,
      * StringUtils.indexOf("", *)           = -1
      * StringUtils.indexOf("aabaabaa", 'a') = 0
      * StringUtils.indexOf("aabaabaa", 'b') = 2
+     * StringUtils.indexOf("aaaaaaaa", 'Z') = -1
      * </pre>
      *
      * @param seq  the CharSequence to check, may be null