diff --git a/source/org/jivesoftware/smackx/bytestreams/ibb/InBandBytestreamSession.java b/source/org/jivesoftware/smackx/bytestreams/ibb/InBandBytestreamSession.java
index 932fdc633..1cced78b2 100644
--- a/source/org/jivesoftware/smackx/bytestreams/ibb/InBandBytestreamSession.java
+++ b/source/org/jivesoftware/smackx/bytestreams/ibb/InBandBytestreamSession.java
@@ -594,7 +594,7 @@ public class InBandBytestreamSession implements BytestreamSession {
          * Constructor.
          */
         public IBBOutputStream() {
-            this.buffer = new byte[byteStreamRequest.getBlockSize()];
+            this.buffer = new byte[(byteStreamRequest.getBlockSize()/4)*3];
         }
 
         /**