diff --git a/CHANGES.txt b/CHANGES.txt
index 73a6717c08..3a2d8781c0 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -4,6 +4,7 @@
  * fix data streaming on windows (CASSANDRA-630)
  * GC compacted sstables after cleanup and compaction (CASSANDRA-621)
  * Speed up anti-entropy validation (CASSANDRA-629)
+ * Fix anti-entropy assertion error (CASSANDRA-639)
  * Fix pending range conflicts when bootstapping or moving
    multiple nodes at once (CASSANDRA-603)
 
diff --git a/src/java/org/apache/cassandra/utils/MerkleTree.java b/src/java/org/apache/cassandra/utils/MerkleTree.java
index 5cf46cd20d..2cc47c122f 100644
--- a/src/java/org/apache/cassandra/utils/MerkleTree.java
+++ b/src/java/org/apache/cassandra/utils/MerkleTree.java
@@ -51,7 +51,7 @@ public class MerkleTree implements Serializable
 {
     private static final long serialVersionUID = 2L;
 
-    public static final byte RECOMMENDED_DEPTH = Byte.MAX_VALUE;
+    public static final byte RECOMMENDED_DEPTH = Byte.MAX_VALUE - 1;
 
     public static final int CONSISTENT = 0;
     public static final int FULLY_INCONSISTENT = 1;
@@ -73,6 +73,7 @@ public class MerkleTree implements Serializable
      */
     public MerkleTree(IPartitioner partitioner, byte hashdepth, long maxsize)
     {
+        assert hashdepth < Byte.MAX_VALUE;
         this.partitioner = partitioner;
         this.hashdepth = hashdepth;
         this.maxsize = maxsize;