diff --git a/src/main/java/org/apache/commons/lang3/text/translate/OctalUnescaper.java b/src/main/java/org/apache/commons/lang3/text/translate/OctalUnescaper.java
index 47a43901a..15fcf13ec 100644
--- a/src/main/java/org/apache/commons/lang3/text/translate/OctalUnescaper.java
+++ b/src/main/java/org/apache/commons/lang3/text/translate/OctalUnescaper.java
@@ -62,10 +62,20 @@ public int translate(final CharSequence input, final int index, final Writer out
         return 0;
     }
 
+    /**
+     * Checks if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7.
+     * @param ch the char to check
+     * @return true if the given char is the character representation of one of the digits from 0 to 7
+     */
     private boolean isOctalDigit(char ch) {
         return ch >= '0' && ch <= '7';
     }
 
+    /**
+     * Checks if the given char is the character representation of one of the digit from 0 to 3.
+     * @param ch the char to check
+     * @return true if the given char is the character representation of one of the digits from 0 to 3
+     */
     private boolean isZeroToThree(char ch) {
         return ch >= '0' && ch <= '3';
     }