diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 30f6dd06ab..06a0dcf8eb 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -87,7 +87,7 @@ type feeHistoryResult struct {
 	GasUsedRatio []float64        `json:"gasUsedRatio"`
 }
 
-func (s *PublicEthereumAPI) FeeHistory(ctx context.Context, blockCount hexutil.Uint, lastBlock rpc.BlockNumber, rewardPercentiles []float64) (*feeHistoryResult, error) {
+func (s *PublicEthereumAPI) FeeHistory(ctx context.Context, blockCount rpc.DecimalOrHex, lastBlock rpc.BlockNumber, rewardPercentiles []float64) (*feeHistoryResult, error) {
 	oldest, reward, baseFee, gasUsed, err := s.b.FeeHistory(ctx, int(blockCount), lastBlock, rewardPercentiles)
 	if err != nil {
 		return nil, err
diff --git a/rpc/types.go b/rpc/types.go
index d1b878c785..ad068defa8 100644
--- a/rpc/types.go
+++ b/rpc/types.go
@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math"
+	"strconv"
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -191,3 +192,24 @@ func BlockNumberOrHashWithHash(hash common.Hash, canonical bool) BlockNumberOrHa
 		RequireCanonical: canonical,
 	}
 }
+
+// DecimalOrHex unmarshals a non-negative decimal or hex parameter into a uint64.
+type DecimalOrHex uint64
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (dh *DecimalOrHex) UnmarshalJSON(data []byte) error {
+	input := strings.TrimSpace(string(data))
+	if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
+		input = input[1 : len(input)-1]
+	}
+
+	value, err := strconv.ParseUint(input, 10, 64)
+	if err != nil {
+		value, err = hexutil.DecodeUint64(input)
+	}
+	if err != nil {
+		return err
+	}
+	*dh = DecimalOrHex(value)
+	return nil
+}