From 758100252385068f960bfce4cbddbf7f0a0d2f7f Mon Sep 17 00:00:00 2001
From: Matt Smith <matt.joseph.smith@gmail.com>
Date: Mon, 14 Jan 2019 17:54:47 -0500
Subject: [PATCH] Fix segfault on DGW

---
 src/pow.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/pow.cpp b/src/pow.cpp
index 7d908523c..4e6adb4d8 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -18,9 +18,8 @@ unsigned int static DarkGravityWave(const CBlockIndex* pindexLast, const CBlockH
     int64_t nPastBlocks = 24;
 
     // make sure we have at least (nPastBlocks + 1) blocks, otherwise just return powLimit
-    if (!pblock || !pindexLast || pindexLast->nHeight < nPastBlocks) {
+    if (pblock == nullptr || pindexLast == nullptr || pindexLast->nHeight < nPastBlocks)
         return bnPowLimit.GetCompact();
-    }
 
     if (params.fPowAllowMinDifficultyBlocks) {
         // recent block is more than 2 hours old
@@ -56,6 +55,9 @@ unsigned int static DarkGravityWave(const CBlockIndex* pindexLast, const CBlockH
 
     arith_uint256 bnNew(bnPastTargetAvg);
 
+    if(pindex == nullptr || pindexLast == nullptr)
+        return bnPowLimit.GetCompact();
+
     int64_t nActualTimespan = pindexLast->GetBlockTime() - pindex->GetBlockTime();
     // NOTE: is this accurate? nActualTimespan counts it for (nPastBlocks - 1) blocks only...
     int64_t nTargetTimespan = nPastBlocks * params.nPowTargetSpacing * NUM_ALGOS;