diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index eaa743fe34..c7d1e0020f 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -963,6 +963,9 @@ func DoEstimateGas(ctx context.Context, b Backend, args CallArgs, blockNrOrHash
 		if err != nil {
 			return 0, err
 		}
+		if block == nil {
+			return 0, errors.New("block not found")
+		}
 		hi = block.GasLimit()
 	}
 	// Recap the highest gas limit with account's available balance.
diff --git a/internal/web3ext/web3ext.go b/internal/web3ext/web3ext.go
index 300c2b054f..e2b8ad1718 100644
--- a/internal/web3ext/web3ext.go
+++ b/internal/web3ext/web3ext.go
@@ -500,6 +500,13 @@ web3._extend({
 			params: 1,
 			inputFormatter: [web3._extend.formatters.inputTransactionFormatter]
 		}),
+		new web3._extend.Method({
+			name: 'estimateGas',
+			call: 'eth_estimateGas',
+			params: 2,
+			inputFormatter: [web3._extend.formatters.inputCallFormatter, web3._extend.formatters.inputBlockNumberFormatter],
+			outputFormatter: web3._extend.utils.toDecimal
+		}),
 		new web3._extend.Method({
 			name: 'submitTransaction',
 			call: 'eth_submitTransaction',