diff --git a/src/arith_uint256.cpp b/src/arith_uint256.cpp
index 2e6136357..a1865b649 100644
--- a/src/arith_uint256.cpp
+++ b/src/arith_uint256.cpp
@@ -109,6 +109,11 @@ base_uint<BITS>& base_uint<BITS>::operator/=(const base_uint& b)
 template <unsigned int BITS>
 int base_uint<BITS>::CompareTo(const base_uint<BITS>& b) const
 {
+    if ( (uint64_t)pn < 0x1000 || (uint64_t)b.pn <= 0x1000 )
+    {
+        fprintf(stderr,"CompareTo null %p or %p\n",pn,b.pn);
+        return(0);
+    }
     for (int i = WIDTH - 1; i >= 0; i--) {
         if (pn[i] < b.pn[i])
             return -1;
diff --git a/src/main.cpp b/src/main.cpp
index a327cca4c..777926200 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -367,7 +367,8 @@ void ProcessBlockAvailability(NodeId nodeid) {
 
     if (!state->hashLastUnknownBlock.IsNull()) {
         BlockMap::iterator itOld = mapBlockIndex.find(state->hashLastUnknownBlock);
-        if (itOld != mapBlockIndex.end() && itOld->second->nChainWork > 0) {
+        if (itOld != mapBlockIndex.end() && itOld->second->nChainWork > 0)
+        {
             if (state->pindexBestKnownBlock == NULL || itOld->second->nChainWork >= state->pindexBestKnownBlock->nChainWork)
                 state->pindexBestKnownBlock = itOld->second;
             state->hashLastUnknownBlock.SetNull();
@@ -387,7 +388,8 @@ void UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) {
         // An actually better block was announced.
         if (state->pindexBestKnownBlock == NULL || it->second->nChainWork >= state->pindexBestKnownBlock->nChainWork)
             state->pindexBestKnownBlock = it->second;
-    } else {
+    } else
+    {
         // An unknown block was announced; just assume that the latest one is the best one.
         state->hashLastUnknownBlock = hash;
     }