diff --git a/common/hexutil/hexutil.go b/common/hexutil/hexutil.go
index a8aa2a6456..ca8a4ae0ef 100644
--- a/common/hexutil/hexutil.go
+++ b/common/hexutil/hexutil.go
@@ -185,7 +185,6 @@ func EncodeBig(bigint *big.Int) string {
 	}
 }
 
-// Add more comprehensive check to validate a hex string
 func IsValidHexString(input string) bool {
 	if !has0xPrefix(input) {
 		return false
diff --git a/common/hexutil/hexutil_test.go b/common/hexutil/hexutil_test.go
index f2b800d82c..5c89fa8c9d 100644
--- a/common/hexutil/hexutil_test.go
+++ b/common/hexutil/hexutil_test.go
@@ -22,6 +22,11 @@ import (
 	"testing"
 )
 
+type hexValidityTest struct {
+	input string
+	want  bool
+}
+
 type marshalTest struct {
 	input interface{}
 	want  string
@@ -134,6 +139,12 @@ var (
 		{input: `0xbbb`, want: uint64(0xbbb)},
 		{input: `0xffffffffffffffff`, want: uint64(0xffffffffffffffff)},
 	}
+
+	hexStringValidityTest = []hexValidityTest{
+		{"0x", false},
+		{"asdcc", false},
+		{"0x00000102", true},
+	}
 )
 
 func TestEncode(t *testing.T) {
@@ -202,6 +213,15 @@ func TestDecodeUint64(t *testing.T) {
 	}
 }
 
+func TestIsValidHexString(t *testing.T) {
+	for _, test := range hexStringValidityTest {
+		actual := IsValidHexString(test.input)
+		if actual != test.want {
+			t.Errorf("input %s: value mismatch: got %t, want %t", test.input, actual, test.want)
+		}
+	}
+}
+
 func BenchmarkEncodeBig(b *testing.B) {
 	for _, bench := range encodeBigTests {
 		b.Run(bench.want, func(b *testing.B) {
diff --git a/rpc/types_test.go b/rpc/types_test.go
index e48db859d4..2a895886b8 100644
--- a/rpc/types_test.go
+++ b/rpc/types_test.go
@@ -42,16 +42,16 @@ func TestBlockNumberJSONUnmarshal(t *testing.T) {
 		6:  {`"0x12"`, false, BlockNumber(18)},
 		7:  {`"0x7fffffffffffffff"`, false, BlockNumber(math.MaxInt64)},
 		8:  {`"0x8000000000000000"`, true, BlockNumber(0)},
-		9:  {"0", true, BlockNumber(0)},
-		10: {`"ff"`, true, BlockNumber(0)},
-		11: {`"pending"`, false, PendingBlockNumber},
-		12: {`"latest"`, false, LatestBlockNumber},
-		13: {`"earliest"`, false, EarliestBlockNumber},
-		14: {`"committed"`, false, CommittedBlockNumber},
-		15: {`"finalized"`, false, CommittedBlockNumber},
-		16: {`someString`, true, BlockNumber(0)},
-		17: {`""`, true, BlockNumber(0)},
-		18: {``, true, BlockNumber(0)},
+		9:  {`"ff"`, true, BlockNumber(0)},
+		10: {`"pending"`, false, PendingBlockNumber},
+		11: {`"latest"`, false, LatestBlockNumber},
+		12: {`"earliest"`, false, EarliestBlockNumber},
+		13: {`"committed"`, false, CommittedBlockNumber},
+		14: {`"finalized"`, false, CommittedBlockNumber},
+		15: {`someString`, true, BlockNumber(0)},
+		16: {`""`, true, BlockNumber(0)},
+		17: {``, true, BlockNumber(0)},
+		18: {`88439993`, false, BlockNumber(88439993)},
 	}
 
 	for i, test := range tests {