diff --git a/src/txdb.cpp b/src/txdb.cpp
index e4b228c114..abae026608 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -277,7 +277,7 @@ bool CBlockTreeDB::LoadBlockIndexGuts(const Consensus::Params& consensusParams,
                 pindexNew->nTx            = diskindex.nTx;
 
                 const uint256 block_hash = pindexNew->GetBlockHash();
-                if (!CheckProofOfWork(block_hash, pindexNew->nBits, consensusParams) &&
+                if (!CheckProof(pindexNew->GetBlockHeader(), consensusParams) &&
                     block_hash != consensusParams.hashGenesisBlock) {
                     return error("%s: CheckProofOfWork: %s, %s", __func__, block_hash.ToString(), pindexNew->ToString());
                 }
diff --git a/src/validation.cpp b/src/validation.cpp
index 918588ebbb..b7fca009bb 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1097,7 +1097,7 @@ bool ReadBlockFromDisk(CBlock& block, const CDiskBlockPos& pos, const Consensus:
 
     // Check the header
     const uint256 block_hash = block.GetHash();
-    if (!CheckProofOfWork(block_hash, block.nBits, consensusParams) &&
+    if (!CheckProof(block, consensusParams) &&
         block_hash != consensusParams.hashGenesisBlock) {
         return error("ReadBlockFromDisk: Errors in block header at %s", pos.ToString());
     }
@@ -3106,8 +3106,8 @@ static bool CheckBlockHeader(const CBlockHeader& block, CValidationState& state,
 {
     // Check proof of work matches claimed amount
     if (fCheckPOW && block.GetHash() != consensusParams.hashGenesisBlock
-            && !CheckProofOfWork(block.GetHash(), block.nBits, consensusParams)) {
-        return state.DoS(50, false, REJECT_INVALID, "high-hash", false, "proof of work failed");
+            && !CheckProof(block, consensusParams)) {
+        return state.DoS(50, false, REJECT_INVALID, g_signed_blocks ? "block-proof-invalid" : "high-hash", false, "proof of work failed");
     }
     return true;
 }
@@ -3257,9 +3257,9 @@ static bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationSta
     assert(pindexPrev != nullptr);
     const int nHeight = pindexPrev->nHeight + 1;
 
-    // Check proof of work
+    // Check proof of work if necessary
     const Consensus::Params& consensusParams = params.GetConsensus();
-    if (block.nBits != GetNextWorkRequired(pindexPrev, &block, consensusParams))
+    if (!CheckChallenge(block, *pindexPrev, consensusParams))
         return state.DoS(100, false, REJECT_INVALID, "bad-diffbits", false, "incorrect proof of work");
 
     // Check against checkpoints