diff --git a/src/com/google/bitcoin/core/Block.java b/src/com/google/bitcoin/core/Block.java
index ae70c7d3..fe1d87be 100644
--- a/src/com/google/bitcoin/core/Block.java
+++ b/src/com/google/bitcoin/core/Block.java
@@ -33,7 +33,7 @@ import static com.google.bitcoin.core.Utils.*;
  * you grab it from a downloaded {@link BlockChain}.
  */
 public class Block extends Message {
-    private static final long serialVersionUID = -2834162413473103042L;
+    private static final long serialVersionUID = 2738848929966035281L;
 
     static final long ALLOWED_TIME_DRIFT = 2 * 60 * 60;  // Same value as official client.
     /** A value for difficultyTarget (nBits) that allows half of all possible hash solutions. Used in unit testing. */