diff --git a/bson/src/main/org/bson/io/OutputBuffer.java b/bson/src/main/org/bson/io/OutputBuffer.java
index e0a1a314017..d4ae12d4245 100644
--- a/bson/src/main/org/bson/io/OutputBuffer.java
+++ b/bson/src/main/org/bson/io/OutputBuffer.java
@@ -197,6 +197,14 @@ public void writeLong(final long value) {
         writeInt64(value);
     }
 
+    /**
+     * Writes the characters of a string to the buffer as UTF-8 bytes.
+     *
+     * @param str the string to write.
+     * @param checkForNullCharacters if true, check for and disallow null characters in the string.
+     * @return the total number of bytes written.
+     * @throws BsonSerializationException if checkForNullCharacters is true and the string contains a null character.
+     */
     protected int writeCharacters(final String str, final boolean checkForNullCharacters) {
         int len = str.length();
         int total = 0;