diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 477ba40118..d8103c926a 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -919,7 +919,7 @@ func (diff *StateOverride) Apply(state *state.StateDB) error {
 // BlockOverrides is a set of header fields to override.
 type BlockOverrides struct {
 	Number     *hexutil.Big
-	Difficulty *hexutil.Big
+	Difficulty *hexutil.Big // No-op if we're simulating post-merge calls.
 	Time       *hexutil.Uint64
 	GasLimit   *hexutil.Uint64
 	Coinbase   *common.Address
@@ -1141,8 +1141,18 @@ func (s *BlockChainAPI) Multicall(ctx context.Context, blocks []CallBatch, block
 		// Each tx and all the series of txes shouldn't consume more gas than cap
 		globalGasCap = s.b.RPCGasCap()
 		gp           = new(core.GasPool).AddGas(globalGasCap)
+		prevNumber   = header.Number.Uint64()
 	)
 	for bi, block := range blocks {
+		blockContext := core.NewEVMBlockContext(header, NewChainContext(ctx, s.b), nil)
+		if block.BlockOverrides != nil {
+			block.BlockOverrides.Apply(&blockContext)
+		}
+		// TODO: Consider hoisting this check up
+		if blockContext.BlockNumber.Uint64() < prevNumber {
+			return nil, fmt.Errorf("block numbers must be in order")
+		}
+		prevNumber = blockContext.BlockNumber.Uint64()
 		// State overrides are applied prior to execution of a block
 		if err := block.StateOverrides.Apply(state); err != nil {
 			return nil, err
@@ -1151,10 +1161,6 @@ func (s *BlockChainAPI) Multicall(ctx context.Context, blocks []CallBatch, block
 		if block.ECRecoverOverride != nil {
 			state.SetCode(common.BytesToAddress([]byte{1}), *block.ECRecoverOverride)
 		}
-		blockContext := core.NewEVMBlockContext(header, NewChainContext(ctx, s.b), nil)
-		if block.BlockOverrides != nil {
-			block.BlockOverrides.Apply(&blockContext)
-		}
 		results[bi] = make([]callResult, len(block.Calls))
 		for i, call := range block.Calls {
 			// Hack to get logs from statedb which stores logs by txhash.
diff --git a/internal/ethapi/api_test.go b/internal/ethapi/api_test.go
index 3cc27e28d0..12682afb33 100644
--- a/internal/ethapi/api_test.go
+++ b/internal/ethapi/api_test.go
@@ -758,18 +758,6 @@ func TestMulticall(t *testing.T) {
 						0x60, 0x20, 0x60, 0x00, 0xf3,
 					},
 				}},
-			}, {
-				// No block number override, should use latest
-				Calls: []TransactionArgs{
-					{
-						From: &accounts[0].addr,
-						Input: &hexutil.Bytes{
-							0x43,             // NUMBER
-							0x60, 0x00, 0x52, // MSTORE offset 0
-							0x60, 0x20, 0x60, 0x00, 0xf3, // RETURN
-						},
-					},
-				},
 			}},
 			want: [][]res{{
 				res{
@@ -781,13 +769,39 @@ func TestMulticall(t *testing.T) {
 					ReturnValue: "0x000000000000000000000000000000000000000000000000000000000000000c",
 					GasUsed:     "0xe891",
 				},
-			}, {
-				res{
-					ReturnValue: "0x000000000000000000000000000000000000000000000000000000000000000a",
-					GasUsed:     "0xe891",
-				},
 			}},
 		},
+		// Block numbers must be in order.
+		{
+			tag: latest,
+			blocks: []CallBatch{{
+				BlockOverrides: &BlockOverrides{
+					Number: (*hexutil.Big)(big.NewInt(12)),
+				},
+				Calls: []TransactionArgs{{
+					From: &accounts[1].addr,
+					Input: &hexutil.Bytes{
+						0x43,             // NUMBER
+						0x60, 0x00, 0x52, // MSTORE offset 0
+						0x60, 0x20, 0x60, 0x00, 0xf3, // RETURN
+					},
+				}},
+			}, {
+				BlockOverrides: &BlockOverrides{
+					Number: (*hexutil.Big)(big.NewInt(11)),
+				},
+				Calls: []TransactionArgs{{
+					From: &accounts[0].addr,
+					Input: &hexutil.Bytes{
+						0x43,             // NUMBER
+						0x60, 0x00, 0x52, // MSTORE offset 0
+						0x60, 0x20, 0x60, 0x00, 0xf3, // RETURN
+					},
+				}},
+			}},
+			want:      [][]res{},
+			expectErr: errors.New("block numbers must be in order"),
+		},
 		// Test on solidity storage example. Set value in one call, read in next.
 		{
 			tag: latest,
@@ -915,7 +929,10 @@ func TestMulticall(t *testing.T) {
 				continue
 			}
 			if !errors.Is(err, tc.expectErr) {
-				t.Errorf("test %d: error mismatch, want %v, have %v", i, tc.expectErr, err)
+				// Second try
+				if !reflect.DeepEqual(err, tc.expectErr) {
+					t.Errorf("test %d: error mismatch, want %v, have %v", i, tc.expectErr, err)
+				}
 			}
 			continue
 		}