diff --git a/README.md b/README.md
index 874383d..9cd685a 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ allprojects {
 project build.gradle
 ```groovy
 dependencies {
-    commonMainApi("dev.icerock.moko:web3:0.11.0")
+    commonMainApi("dev.icerock.moko:web3:0.12.0")
 }
 ```
 
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 8504db2..5eaac71 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -9,7 +9,7 @@ kbignumVersion = "2.2.0"
 klockVersion = "2.2.2"
 ktorClientVersion = "1.6.1"
 mokoTestVersion = "0.4.0"
-mokoWeb3Version = "0.11.0"
+mokoWeb3Version = "0.12.0"
 multidexVersion = "2.0.1"
 
 [libraries]
diff --git a/web3/src/commonMain/kotlin/dev.icerock.moko.web3/TransactionHash.kt b/web3/src/commonMain/kotlin/dev.icerock.moko.web3/TransactionHash.kt
index 5d84286..e015123 100644
--- a/web3/src/commonMain/kotlin/dev.icerock.moko.web3/TransactionHash.kt
+++ b/web3/src/commonMain/kotlin/dev.icerock.moko.web3/TransactionHash.kt
@@ -6,10 +6,26 @@ package dev.icerock.moko.web3
 
 import dev.icerock.moko.web3.hex.Hex32String
 import kotlinx.serialization.Serializable
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
 
-@Serializable
+@Serializable(with = TransactionHash.Serializer::class)
 class TransactionHash(private val value: String) : Hex32String by Hex32String(value) {
-    override fun toString() = withoutPrefix 
+    override fun toString() = withoutPrefix
     override fun hashCode(): Int = withoutPrefix.hashCode()
     override fun equals(other: Any?): Boolean = other is TransactionHash && other.withoutPrefix == withoutPrefix
+
+    @kotlinx.serialization.Serializer(forClass = TransactionHash::class)
+    object Serializer {
+        override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor(
+            serialName = "dev.icerock.mokoWeb3.TransactionHash",
+            kind = PrimitiveKind.STRING
+        )
+
+        override fun deserialize(decoder: Decoder): TransactionHash = TransactionHash(decoder.decodeString())
+        override fun serialize(encoder: Encoder, value: TransactionHash) = encoder.encodeString(value.value)
+    }
 }
diff --git a/web3/src/commonMain/kotlin/dev.icerock.moko.web3/contract/StaticEncoders.kt b/web3/src/commonMain/kotlin/dev.icerock.moko.web3/contract/StaticEncoders.kt
index 10615e5..2dd8200 100644
--- a/web3/src/commonMain/kotlin/dev.icerock.moko.web3/contract/StaticEncoders.kt
+++ b/web3/src/commonMain/kotlin/dev.icerock.moko.web3/contract/StaticEncoders.kt
@@ -8,6 +8,7 @@ enum class StaticEncoders(
     val typeAnnotation: String,
     val encoder: StaticEncoder<*>
 ) {
+    UInt8(typeAnnotation = "uint8", encoder = UInt256Param),
     UInt256(typeAnnotation = "uint256", encoder = UInt256Param),
     Address(typeAnnotation = "address", encoder = AddressParam);
 
diff --git a/web3/src/commonMain/kotlin/dev.icerock.moko.web3/hex/HexStringValueClass.kt b/web3/src/commonMain/kotlin/dev.icerock.moko.web3/hex/HexStringValueClass.kt
index e82f025..39ae8b9 100644
--- a/web3/src/commonMain/kotlin/dev.icerock.moko.web3/hex/HexStringValueClass.kt
+++ b/web3/src/commonMain/kotlin/dev.icerock.moko.web3/hex/HexStringValueClass.kt
@@ -15,7 +15,7 @@ internal class HexStringValueClass(private val value: String): HexString {
 
     override val withoutPrefix: String get() = value.removePrefix(HEX_PREFIX)
     override val prefixed: String get() = "$HEX_PREFIX$withoutPrefix"
-    override val bigInt: BigInt get() = value.bi(RADIX)
+    override val bigInt: BigInt get() = withoutPrefix.bi(RADIX)
 
     override fun toString() = withoutPrefix 
     override fun hashCode(): Int = withoutPrefix.hashCode()