diff --git a/core/src/main/scala/spark/storage/BlockManager.scala b/core/src/main/scala/spark/storage/BlockManager.scala
index ff9914ae25..45f99717bc 100644
--- a/core/src/main/scala/spark/storage/BlockManager.scala
+++ b/core/src/main/scala/spark/storage/BlockManager.scala
@@ -364,6 +364,12 @@ class BlockManager(val master: BlockManagerMaster, val serializer: Serializer, m
 
     val startTimeMs = System.currentTimeMillis 
     var bytes: ByteBuffer = null
+
+    // If we need to replicate the data, we'll want access to the values, but because our
+    // put will read the whole iterator, there will be no values left. For the case where
+    // the put serializes data, we'll remember the bytes, above; but for the case where
+    // it doesn't, such as MEMORY_ONLY_DESER, let's rely on the put returning an Iterator.
+    var valuesAfterPut: Iterator[Any] = null
     
     locker.getLock(blockId).synchronized {
       logDebug("Put for block " + blockId + " took " + Utils.getUsedTimeMs(startTimeMs)
@@ -391,7 +397,7 @@ class BlockManager(val master: BlockManagerMaster, val serializer: Serializer, m
         // If only save to memory 
         memoryStore.putValues(blockId, values, level) match {
           case Right(newBytes) => bytes = newBytes
-          case _ => 
+          case Left(newIterator) => valuesAfterPut = newIterator
         }
       } else {
         // If only save to disk
@@ -408,8 +414,13 @@ class BlockManager(val master: BlockManagerMaster, val serializer: Serializer, m
 
     // Replicate block if required 
     if (level.replication > 1) {
+      // Serialize the block if not already done
       if (bytes == null) {
-        bytes = dataSerialize(values) // serialize the block if not already done
+        if (valuesAfterPut == null) {
+          throw new SparkException(
+            "Underlying put returned neither an Iterator nor bytes! This shouldn't happen.")
+        }
+        bytes = dataSerialize(valuesAfterPut)
       }
       replicate(blockId, bytes, level) 
     }