diff --git a/rlp/encodel.go b/rlp/encodel.go
index 0cb5c35ce..cbbe0637c 100644
--- a/rlp/encodel.go
+++ b/rlp/encodel.go
@@ -62,19 +62,76 @@ func U64Len(i uint64) int {
 }
 
 func EncodeU64(i uint64, to []byte) int {
-	if i > 128 {
-		beLen := (bits.Len64(i) + 7) / 8
-		to[0] = 128 + byte(beLen)
-		binary.BigEndian.PutUint64(to[1:], i)
-		copy(to[1:], to[1+8-beLen:1+8])
-		return 1 + beLen
-	}
 	if i == 0 {
 		to[0] = 128
 		return 1
 	}
-	to[0] = byte(i)
-	return 1
+	if i < 128 {
+		to[0] = byte(i) // fits single byte
+		return 1
+	}
+
+	b := to[1:]
+	l := 0
+
+	// writes i to b in big endian byte order, using the least number of bytes needed to represent i.
+	switch {
+	case i < (1 << 8):
+		b[0] = byte(i)
+		l = 1
+	case i < (1 << 16):
+		b[0] = byte(i >> 8)
+		b[1] = byte(i)
+		l = 2
+	case i < (1 << 24):
+		b[0] = byte(i >> 16)
+		b[1] = byte(i >> 8)
+		b[2] = byte(i)
+		l = 3
+	case i < (1 << 32):
+		b[0] = byte(i >> 24)
+		b[1] = byte(i >> 16)
+		b[2] = byte(i >> 8)
+		b[3] = byte(i)
+		l = 4
+	case i < (1 << 40):
+		b[0] = byte(i >> 32)
+		b[1] = byte(i >> 24)
+		b[2] = byte(i >> 16)
+		b[3] = byte(i >> 8)
+		b[4] = byte(i)
+		l = 5
+	case i < (1 << 48):
+		b[0] = byte(i >> 40)
+		b[1] = byte(i >> 32)
+		b[2] = byte(i >> 24)
+		b[3] = byte(i >> 16)
+		b[4] = byte(i >> 8)
+		b[5] = byte(i)
+		l = 6
+	case i < (1 << 56):
+		b[0] = byte(i >> 48)
+		b[1] = byte(i >> 40)
+		b[2] = byte(i >> 32)
+		b[3] = byte(i >> 24)
+		b[4] = byte(i >> 16)
+		b[5] = byte(i >> 8)
+		b[6] = byte(i)
+		l = 7
+	default:
+		b[0] = byte(i >> 56)
+		b[1] = byte(i >> 48)
+		b[2] = byte(i >> 40)
+		b[3] = byte(i >> 32)
+		b[4] = byte(i >> 24)
+		b[5] = byte(i >> 16)
+		b[6] = byte(i >> 8)
+		b[7] = byte(i)
+		l = 8
+	}
+
+	to[0] = 128 + byte(l)
+	return 1 + l
 }
 
 func StringLen(sLen int) int {
diff --git a/txpool/pool_fuzz_test.go b/txpool/pool_fuzz_test.go
index 456e8d2cd..2a3a6e829 100644
--- a/txpool/pool_fuzz_test.go
+++ b/txpool/pool_fuzz_test.go
@@ -255,7 +255,7 @@ func fakeRlpTx(slot *TxSlot, data []byte) []byte {
 	buf[0] = byte(DynamicFeeTxType)
 	p := 1
 	p += rlp.EncodeListPrefix(dataLen, buf[p:])
-	p += rlp.EncodeU64(1, buf[p:])
+	p += rlp.EncodeU64(1, buf[p:]) //chainID
 	p += rlp.EncodeU64(slot.nonce, buf[p:])
 	p += rlp.EncodeU64(slot.tip, buf[p:])
 	p += rlp.EncodeU64(slot.feeCap, buf[p:])