diff --git a/src/java/hep/lcio/implementation/sio/SIOTrack.java b/src/java/hep/lcio/implementation/sio/SIOTrack.java
index 1ef2bec1b..5ce01f0a9 100644
--- a/src/java/hep/lcio/implementation/sio/SIOTrack.java
+++ b/src/java/hep/lcio/implementation/sio/SIOTrack.java
@@ -89,13 +89,15 @@ class SIOTrack extends ITrack
          hitNumbers[i] = in.readInt() ;
       }
       setSubdetectorHitNumbers(hitNumbers) ;
-      int nHoleNumbers = in.readInt() ;
-      int[] holeNumbers = new int[nHoleNumbers] ;
-      for (int i = 0; i < nHoleNumbers; i++)
-      {
-         holeNumbers[i] = in.readInt() ;
+      if (SIOVersion.encode(major,minor) > SIOVersion.encode(2,21) {
+         int nHoleNumbers = in.readInt() ;
+         int[] holeNumbers = new int[nHoleNumbers] ;
+         for (int i = 0; i < nHoleNumbers; i++)
+         {
+            holeNumbers[i] = in.readInt() ;
+         }
+         setSubdetectorHoleNumbers(holeNumbers) ;
       }
-      setSubdetectorHoleNumbers(holeNumbers) ;
       int nTracks = in.readInt();
       tempTracks = new ArrayList(nTracks);
       tracks = null;