diff --git a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/block/BlockDisk.java b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/block/BlockDisk.java
index 5c7a7fa..b6ceaf7 100644
--- a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/block/BlockDisk.java
+++ b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/block/BlockDisk.java
@@ -393,7 +393,7 @@
      */
     protected long calculateByteOffsetForBlockAsLong( int block )
     {
-        return block * blockSizeBytes;
+        return (long) block * blockSizeBytes;
     }
 
     /**