diff --git a/codec/postprocess.go b/codec/postprocess.go
index 27ed1714..fa991a0c 100644
--- a/codec/postprocess.go
+++ b/codec/postprocess.go
@@ -172,7 +172,7 @@ func CombinePolygonSystemTransactions(traces []*pbeth.TransactionTrace, blockNum
 	var unmergeableSystemTransactions []*pbeth.TransactionTrace
 	normalTransactions := make([]*pbeth.TransactionTrace, 0, len(traces))
 
-	var highestTrxIndex uint32
+	highestTrxIndex := int64(-1) // negative so that next one is 0 if no normal transaction is met
 	for _, trace := range traces {
 		if bytes.Equal(trace.From, polygonSystemAddress) {
 			if bytes.Equal(trace.To, polygonStateReceiverAddress) {
@@ -185,8 +185,8 @@ func CombinePolygonSystemTransactions(traces []*pbeth.TransactionTrace, blockNum
 			}
 			// no other know case for polygon
 		}
-		if trace.Index > highestTrxIndex {
-			highestTrxIndex = trace.Index
+		if int64(trace.Index) > highestTrxIndex {
+			highestTrxIndex = int64(trace.Index)
 		}
 		normalTransactions = append(normalTransactions, trace)
 	}
@@ -282,7 +282,7 @@ func CombinePolygonSystemTransactions(traces []*pbeth.TransactionTrace, blockNum
 			GasPrice:     bigIntZero,
 			GasLimit:     0,
 			Value:        bigIntZero,
-			Index:        highestTrxIndex + 1,
+			Index:        uint32(highestTrxIndex + 1),
 			Input:        nil,
 			GasUsed:      0,
 			Type:         pbeth.TransactionTrace_TRX_TYPE_LEGACY,
@@ -302,7 +302,7 @@ func CombinePolygonSystemTransactions(traces []*pbeth.TransactionTrace, blockNum
 		highestTrxIndex++
 	}
 	for _, tx := range unmergeableSystemTransactions {
-		tx.Index = highestTrxIndex + 1
+		tx.Index = uint32(highestTrxIndex + 1)
 		systemTransactionHashes = append(systemTransactionHashes, tx.Hash)
 		out = append(out, tx)
 		highestTrxIndex++
diff --git a/codec/postprocess_test.go b/codec/postprocess_test.go
index 8b6f8679..cf059cfc 100644
--- a/codec/postprocess_test.go
+++ b/codec/postprocess_test.go
@@ -63,6 +63,7 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 		expectedSystemTrxBeginOrdinal uint64
 		expectedSystemTrxEndOrdinal   uint64
 		expectedSystemTrx             bool
+		expectedSystemTrxIndex        uint32
 		expectedCalls                 []*pbeth.Call
 	}{
 		{
@@ -75,6 +76,7 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 			0,
 			0,
 			false,
+			0,
 			nil,
 		},
 		{
@@ -90,6 +92,24 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 			1,
 			4,
 			true,
+			2,
+			[]*pbeth.Call{
+				call(1, 0, 0, 2, 3),
+				call(2, 1, 1, 2, 3),
+			},
+		},
+		{
+			"single system trx, no normal trx",
+			[]*pbeth.TransactionTrace{
+				systemTrx("cc", 1, 4, []*pbeth.Call{
+					call(1, 0, 0, 2, 3),
+				}),
+			},
+			[]string{systemTrxHash},
+			1,
+			4,
+			true,
+			0,
 			[]*pbeth.Call{
 				call(1, 0, 0, 2, 3),
 				call(2, 1, 1, 2, 3),
@@ -110,6 +130,7 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 			1,
 			10,
 			true,
+			1,
 			[]*pbeth.Call{
 				call(1, 0, 0, 2, 9),
 				call(2, 1, 1, 2, 9),
@@ -146,6 +167,7 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 			1,
 			30,
 			true,
+			1,
 			[]*pbeth.Call{
 				call(1, 0, 0, 2, 29),
 
@@ -170,6 +192,11 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 
+			// our test values have no index set, we set it here to check the combination index result
+			for i, tx := range test.in {
+				tx.Index = uint32(i)
+			}
+
 			out, outHashes := CombinePolygonSystemTransactions(test.in, 0, nil)
 
 			if test.expectedSystemTrx {
@@ -193,6 +220,7 @@ func TestCombinePolygonSystemTransactions(t *testing.T) {
 				return
 			}
 
+			assert.Equal(t, test.expectedSystemTrxIndex, systemTrx.Index)
 			assert.Equal(t, test.expectedSystemTrxBeginOrdinal, systemTrx.BeginOrdinal)
 			assert.Equal(t, test.expectedSystemTrxEndOrdinal, systemTrx.EndOrdinal)
 
diff --git a/codec/testdata/polygon_calls_after_finalize.dmlog.golden.json b/codec/testdata/polygon_calls_after_finalize.dmlog.golden.json
index 0a212954..f8842b38 100644
--- a/codec/testdata/polygon_calls_after_finalize.dmlog.golden.json
+++ b/codec/testdata/polygon_calls_after_finalize.dmlog.golden.json
@@ -653,7 +653,6 @@
         "from": "fffffffffffffffffffffffffffffffffffffffe",
         "gasLimit": "9223372036854775807",
         "hash": "958e5726dd1fa45d3f56d56733d86edd09fefebd1a64efccd9b74de65f7a1de0",
-        "index": 1,
         "input": "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",
         "receipt": {
           "logsBloom": "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
@@ -664,4 +663,4 @@
     ],
     "ver": 3
   }
-]
\ No newline at end of file
+]
diff --git a/tools/compare-rpc.go b/tools/compare-rpc.go
index db3dd335..01cb362c 100644
--- a/tools/compare-rpc.go
+++ b/tools/compare-rpc.go
@@ -342,11 +342,6 @@ func stripFirehoseTransactionTraces(in []*pbeth.TransactionTrace, hashesWithoutT
 	idx := uint32(0)
 	for _, trace := range in {
 
-		if trace.Index != idx {
-			if idx == uint32(len(in)-1) {
-				trace.Index = idx // POLYGON BLOCK FIX
-			}
-		}
 		if hashesWithoutTo[eth.Hash(trace.Hash).String()] {
 			trace.To = nil // FIXME: we could compute this from nonce+address
 		}