diff --git a/src/test/java/org/apache/commons/collections4/map/IdentityMap.java b/src/test/java/org/apache/commons/collections4/map/IdentityMap.java
index 50736a898e..d72e1ae47f 100644
--- a/src/test/java/org/apache/commons/collections4/map/IdentityMap.java
+++ b/src/test/java/org/apache/commons/collections4/map/IdentityMap.java
@@ -196,7 +196,10 @@ private void readObject(final ObjectInputStream in) throws IOException, ClassNot
     }
 
     /**
-     * Write the map out using a custom routine.
+     * Serializes this object to an ObjectOutputStream.
+     *
+     * @param out the target ObjectOutputStream.
+     * @throws IOException thrown when an I/O errors occur writing to the target stream.
      */
     private void writeObject(final ObjectOutputStream out) throws IOException {
         out.defaultWriteObject();