diff --git a/processing/src/main/java/io/druid/query/groupby/orderby/OrderByColumnSpec.java b/processing/src/main/java/io/druid/query/groupby/orderby/OrderByColumnSpec.java
index bf0432ad5c9..efb91a9c3c0 100644
--- a/processing/src/main/java/io/druid/query/groupby/orderby/OrderByColumnSpec.java
+++ b/processing/src/main/java/io/druid/query/groupby/orderby/OrderByColumnSpec.java
@@ -185,7 +185,7 @@ public class OrderByColumnSpec
     final byte[] dimensionBytes = dimension.getBytes();
     final byte[] directionBytes = direction.name().getBytes();
 
-    return ByteBuffer.allocate(dimensionBytes.length + dimensionBytes.length)
+    return ByteBuffer.allocate(dimensionBytes.length + directionBytes.length)
                      .put(dimensionBytes)
                      .put(directionBytes)
                      .array();