From 95713f40f146e506569369faffa6d82951c36a1f Mon Sep 17 00:00:00 2001
From: HashEngineering <hashengineeringsolutions@gmail.com>
Date: Wed, 21 Mar 2018 23:39:43 -0700
Subject: [PATCH] DAA:  Fix EDA when using checkpoints.

---
 .../java/org/bitcoinj/params/AbstractBitcoinNetParams.java | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/core/src/main/java/org/bitcoinj/params/AbstractBitcoinNetParams.java b/core/src/main/java/org/bitcoinj/params/AbstractBitcoinNetParams.java
index ab07dbd5769..2b32adf1198 100644
--- a/core/src/main/java/org/bitcoinj/params/AbstractBitcoinNetParams.java
+++ b/core/src/main/java/org/bitcoinj/params/AbstractBitcoinNetParams.java
@@ -95,6 +95,13 @@ public void checkDifficultyTransitions(final StoredBlock storedPrev, final Block
             }
             long mpt6blocks = 0;
             try {
+                //Check to see if there are enough blocks before cursor to correctly calculate the median time
+                StoredBlock beforeCursor = cursor;
+                for (int i = 0; i < 10; i++) {
+                    beforeCursor = blockStore.get(beforeCursor.getHeader().getPrevBlockHash());
+                    if(beforeCursor == null)
+                        return; //Not enough blocks to check difficulty.
+                }
                 mpt6blocks = blockChain.getMedianTimestampOfRecentBlocks(storedPrev, blockStore) - blockChain.getMedianTimestampOfRecentBlocks(cursor, blockStore);
             } catch (NullPointerException x)
             {