diff --git a/eth/catalyst/api.go b/eth/catalyst/api.go
index 6f2d3e76b78e9..80759baddea2d 100644
--- a/eth/catalyst/api.go
+++ b/eth/catalyst/api.go
@@ -305,12 +305,13 @@ func (api *ConsensusAPI) assembleBlock(parentHash common.Hash, params *PayloadAt
 		return nil, fmt.Errorf("cannot assemble block with unknown parent %s", parentHash)
 	}
 
-	if params.Timestamp < parent.Time() {
-		return nil, fmt.Errorf("child timestamp lower than parent's: %d < %d", params.Timestamp, parent.Time())
+	if params.Timestamp <= parent.Time() {
+		return nil, fmt.Errorf("child timestamp lower or equal to parent's: %d < %d", params.Timestamp, parent.Time())
 	}
 	if now := uint64(time.Now().Unix()); params.Timestamp > now+1 {
 		diff := time.Duration(params.Timestamp-now) * time.Second
 		log.Warn("Producing block too far in the future", "diff", common.PrettyDuration(diff))
+		return nil, fmt.Errorf("timestamp too far in the future: %d > %d", params.Timestamp, now)
 	}
 	pending := api.eth.TxPool().Pending(true)
 	coinbase := params.SuggestedFeeRecipient
diff --git a/eth/catalyst/api_test.go b/eth/catalyst/api_test.go
index aa5cb80eef1d3..a9ea2eb5525e4 100644
--- a/eth/catalyst/api_test.go
+++ b/eth/catalyst/api_test.go
@@ -184,6 +184,41 @@ func checkLogEvents(t *testing.T, logsCh <-chan []*types.Log, rmLogsCh <-chan co
 	}
 }
 
+func TestInvalidPayloadTimestamp(t *testing.T) {
+	genesis, preMergeBlocks := generatePreMergeChain(10)
+	n, ethservice := startEthService(t, genesis, preMergeBlocks)
+	ethservice.Merger().ReachTTD()
+	defer n.Close()
+	var (
+		api    = NewConsensusAPI(ethservice, nil)
+		parent = ethservice.BlockChain().CurrentBlock()
+	)
+	tests := []uint64{
+		0,
+		parent.Time(),
+		parent.Time() - 1,
+		uint64(time.Now().Unix()) + uint64(time.Minute),
+	}
+
+	for _, test := range tests {
+		params := PayloadAttributesV1{
+			Timestamp:             test,
+			Random:                crypto.Keccak256Hash([]byte{byte(123)}),
+			SuggestedFeeRecipient: parent.Coinbase(),
+		}
+		fcState := ForkchoiceStateV1{
+			HeadBlockHash:      parent.Hash(),
+			SafeBlockHash:      common.Hash{},
+			FinalizedBlockHash: common.Hash{},
+		}
+		_, err := api.ForkchoiceUpdatedV1(fcState, &params)
+		if err == nil {
+			t.Fatalf("expected error preparing payload with invalid timestamp, err=%v", err)
+		}
+	}
+
+}
+
 func TestEth2NewBlock(t *testing.T) {
 	genesis, preMergeBlocks := generatePreMergeChain(10)
 	n, ethservice := startEthService(t, genesis, preMergeBlocks)
@@ -413,6 +448,5 @@ func TestFullAPI(t *testing.T) {
 			t.Fatalf("Chain head should be updated")
 		}
 		parent = ethservice.BlockChain().CurrentBlock()
-
 	}
 }