diff --git a/core/src/test/java/org/bitcoinj/core/BitcoindComparisonTool.java b/core/src/test/java/org/bitcoinj/core/BitcoindComparisonTool.java
index 352edf51..0538ab95 100644
--- a/core/src/test/java/org/bitcoinj/core/BitcoindComparisonTool.java
+++ b/core/src/test/java/org/bitcoinj/core/BitcoindComparisonTool.java
@@ -287,6 +287,8 @@ public class BitcoindComparisonTool {
                     differingBlocks++;
                     log.error("bitcoind and bitcoinj acceptance differs on block \"" + block.ruleName + "\"");
                 }
+                if (block.sendOnce)
+                    preloadedBlocks.remove(nextBlock.getHash());
                 log.info("Block \"" + block.ruleName + "\" completed processing");
             } else if (rule instanceof MemoryPoolState) {
                 MemoryPoolMessage message = new MemoryPoolMessage();
diff --git a/core/src/test/java/org/bitcoinj/core/FullBlockTestGenerator.java b/core/src/test/java/org/bitcoinj/core/FullBlockTestGenerator.java
index f8e65552..ae9901e0 100644
--- a/core/src/test/java/org/bitcoinj/core/FullBlockTestGenerator.java
+++ b/core/src/test/java/org/bitcoinj/core/FullBlockTestGenerator.java
@@ -56,6 +56,7 @@ class BlockAndValidity extends Rule {
     Sha256Hash blockHash;
     boolean connects;
     boolean throwsException;
+    boolean sendOnce; // We can throw away the memory for this block once we send it the first time (if bitcoind asks again, its broken)
     Sha256Hash hashChainTipAfterBlock;
     int heightAfterBlock;
 
@@ -81,6 +82,11 @@ class BlockAndValidity extends Rule {
         else
             blockToHeightMap.put(hashChainTipAfterBlock, heightAfterBlock);
     }
+
+    public BlockAndValidity setSendOnce(boolean sendOnce) {
+        this.sendOnce = sendOnce;
+        return this;
+    }
 }
 
 /**
@@ -1658,7 +1664,7 @@ public class FullBlockTestGenerator {
                 }
                 block.solve();
                 blocks.add(new BlockAndValidity(blockToHeightMap, hashHeaderMap, block, true, false, block.getHash(), nextHeight-1,
-                                                "post-b1001 repeated transaction generator " + blockCountAfter1001 + "/" + TRANSACTION_CREATION_BLOCKS));
+                                                "post-b1001 repeated transaction generator " + blockCountAfter1001 + "/" + TRANSACTION_CREATION_BLOCKS).setSendOnce(true));
                 lastBlock = block;
             }
 
@@ -1672,7 +1678,8 @@ public class FullBlockTestGenerator {
                     block.addTransaction(tx);
                 }
                 block.solve();
-                blocks.add(new BlockAndValidity(blockToHeightMap, hashHeaderMap, block, true, false, block.getHash(), nextHeight-1, "post-b1001 repeated transaction spender " + i));
+                blocks.add(new BlockAndValidity(blockToHeightMap, hashHeaderMap, block, true, false, block.getHash(), nextHeight-1,
+                                                "post-b1001 repeated transaction spender " + i).setSendOnce(true));
                 lastBlock = block;
                 blockCountAfter1001++;
             }