diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go
index 070937ca5..6815cc83d 100644
--- a/consensus/ethash/consensus.go
+++ b/consensus/ethash/consensus.go
@@ -311,6 +311,8 @@ func (ethash *Ethash) CalcDifficulty(chain consensus.ChainHeaderReader, time uin
 func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {
 	next := new(big.Int).Add(parent.Number, big1)
 	switch {
+	case config.IsPrimordialPulseBlock(next):
+		return params.PulseChainTTDOffset
 	case config.IsGrayGlacier(next):
 		return calcDifficultyEip5133(time, parent)
 	case config.IsArrowGlacier(next):
diff --git a/params/pulse.go b/params/pulse.go
index c32502435..fc99cfc4e 100644
--- a/params/pulse.go
+++ b/params/pulse.go
@@ -12,6 +12,14 @@ type Treasury struct {
 	Balance *math.HexOrDecimal256 `json:"balance"`
 }
 
+// A trivially small amount of work to add to the Ethereum Mainnet TTD
+// to allow for un-merging and merging with the PulseChain beacon chain
+var PulseChainTTDOffset = big.NewInt(131_072)
+
+// This value is defined as LAST_ACTUAL_MAINNET_TTD + PulseChainTTDOffset
+// where LAST_ACTUAL_MAINNET_TTD = 58_750_003_716_598_352_816_469
+var PulseChainTerminalTotalDifficulty, _ = new(big.Int).SetString("58_750_003_716_598_352_947_541", 0)
+
 var (
 	PulseChainConfig = &ChainConfig{
 		ChainID:                       big.NewInt(369),
@@ -30,7 +38,7 @@ var (
 		LondonBlock:                   big.NewInt(12_965_000),
 		ArrowGlacierBlock:             big.NewInt(13_773_000),
 		GrayGlacierBlock:              big.NewInt(15_050_000),
-		TerminalTotalDifficulty:       MainnetTerminalTotalDifficulty, // 58_750_000_000_000_000_000_000
+		TerminalTotalDifficulty:       PulseChainTerminalTotalDifficulty,
 		TerminalTotalDifficultyPassed: true,
 		Ethash:                        new(EthashConfig),
 		PrimordialPulseBlock:          big.NewInt(15_700_000), // TODO: UPDATE FORK BLOCK
@@ -53,7 +61,7 @@ var (
 		LondonBlock:                   big.NewInt(12_965_000),
 		ArrowGlacierBlock:             big.NewInt(13_773_000),
 		GrayGlacierBlock:              big.NewInt(15_050_000),
-		TerminalTotalDifficulty:       MainnetTerminalTotalDifficulty, // 58_750_000_000_000_000_000_000
+		TerminalTotalDifficulty:       PulseChainTerminalTotalDifficulty,
 		TerminalTotalDifficultyPassed: true,
 		Ethash:                        new(EthashConfig),
 		PrimordialPulseBlock:          big.NewInt(15_700_000), // TODO: UPDATE FORK BLOCK