diff --git a/build.gradle.kts b/build.gradle.kts
index 86c019e..ef387a7 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,5 +1,5 @@
 plugins {
-    kotlin("multiplatform") version "1.9.21" apply false
+    kotlin("multiplatform") version "1.9.22" apply false
     id("com.vanniktech.maven.publish") version "0.25.3" apply false
 }
 
diff --git a/rpccore/build.gradle.kts b/rpccore/build.gradle.kts
index 4450fab..4f93941 100644
--- a/rpccore/build.gradle.kts
+++ b/rpccore/build.gradle.kts
@@ -1,6 +1,6 @@
 plugins {
     kotlin("multiplatform")
-    kotlin("plugin.serialization") version "1.9.21"
+    kotlin("plugin.serialization") version "1.9.22"
     id("com.vanniktech.maven.publish")
 }
 
diff --git a/rpccore/src/commonMain/kotlin/com/solana/networking/Rpc20Driver.kt b/rpccore/src/commonMain/kotlin/com/solana/networking/Rpc20Driver.kt
index 3daffc0..68e580d 100644
--- a/rpccore/src/commonMain/kotlin/com/solana/networking/Rpc20Driver.kt
+++ b/rpccore/src/commonMain/kotlin/com/solana/networking/Rpc20Driver.kt
@@ -3,20 +3,31 @@ package com.solana.networking
 import com.solana.rpccore.*
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.json.Json
+import kotlinx.serialization.modules.SerializersModule
+import kotlinx.serialization.modules.polymorphic
+import kotlinx.serialization.modules.subclass
 
 class Rpc20Driver(private val url: String,
-                  private val httpDriver: HttpNetworkDriver) : JsonRpcDriver {
+                  private val httpDriver: HttpNetworkDriver,
+                  private val json: Json) : JsonRpcDriver {
 
-    private val json = Json {
+    constructor(url: String, httpDriver: HttpNetworkDriver) : this(url, httpDriver, Json {
         ignoreUnknownKeys = true
-    }
+    })
 
-    override suspend fun <R> makeRequest(request: RpcRequest, resultSerializer: KSerializer<R>): Rpc20Response<R> =
-        httpDriver.makeHttpRequest(
+    override suspend fun <R> makeRequest(request: RpcRequest, resultSerializer: KSerializer<R>): Rpc20Response<R> {
+        require(request.jsonrpc == "2.0") { "Request is not a JSON RPC 2.0 request (${request.jsonrpc})"}
+        return httpDriver.makeHttpRequest(
             HttpPostRequest(
                 url = url,
                 properties = mapOf("Content-Type" to "application/json; charset=utf-8"),
-                body = json.encodeToString(RpcRequestPolymorphicSerializer, request)
+                body = json.encodeToString(
+                    JsonRpc20Request.serializer(), JsonRpc20Request(
+                        request.method,
+                        request.params,
+                        request.id
+                    )
+                )
             )
         ).run {
             try {
@@ -25,6 +36,7 @@ class Rpc20Driver(private val url: String,
                 Rpc20Response(error = RpcError(-1, e.message ?: this))
             }
         }
+    }
 
     internal class HttpPostRequest(
         override val url: String,
diff --git a/rpccore/src/commonMain/kotlin/com/solana/rpccore/RpcRequest.kt b/rpccore/src/commonMain/kotlin/com/solana/rpccore/RpcRequest.kt
index 838dcea..9dc0460 100644
--- a/rpccore/src/commonMain/kotlin/com/solana/rpccore/RpcRequest.kt
+++ b/rpccore/src/commonMain/kotlin/com/solana/rpccore/RpcRequest.kt
@@ -1,6 +1,5 @@
 package com.solana.rpccore
 
-import kotlinx.serialization.DeserializationStrategy
 import kotlinx.serialization.EncodeDefault
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.*
@@ -30,9 +29,3 @@ open class JsonRpc20Request (
     @EncodeDefault
     override val jsonrpc: String = "2.0"
 }
-
-object RpcRequestPolymorphicSerializer : JsonContentPolymorphicSerializer<RpcRequest>(RpcRequest::class) {
-    override fun selectDeserializer(element: JsonElement): DeserializationStrategy<RpcRequest> {
-        return RpcRequest.serializer()
-    }
-}
diff --git a/rpccore/src/commonTest/kotlin/com/solana/rpccore/RpcCoreTest.kt b/rpccore/src/commonTest/kotlin/com/solana/rpccore/RpcCoreTest.kt
index 62fadca..55b7900 100644
--- a/rpccore/src/commonTest/kotlin/com/solana/rpccore/RpcCoreTest.kt
+++ b/rpccore/src/commonTest/kotlin/com/solana/rpccore/RpcCoreTest.kt
@@ -5,9 +5,8 @@ import com.solana.networking.HttpRequest
 import com.solana.networking.Rpc20Driver
 import com.solana.util.MockHttpDriver
 import kotlinx.coroutines.test.runTest
-import kotlinx.serialization.json.JsonElement
-import kotlinx.serialization.json.buildJsonObject
-import kotlinx.serialization.json.put
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.*
 import kotlin.test.*
 
 class RpcDriverTest {
@@ -139,4 +138,33 @@ class RpcDriverTest {
 
         rpcDriver.makeRequest(rpcRequest)
     }
+
+    @Test
+    fun testRpc20DriverCorrectlySerializesCustomRequest() = runTest {
+        class MyRpcRequest : JsonRpc20Request("getSomething", id = "1234",
+            params = buildJsonArray {
+                add("a string")
+                addJsonObject {
+                    put("param", "value")
+                }
+            })
+
+        val rpcUrl = "https://api.invalid.solana.com"
+        val rpcRequest = MyRpcRequest()
+        val serializedRequest = buildJsonObject {
+            put("method", rpcRequest.method)
+            put("params", rpcRequest.params!!)
+            put("id", rpcRequest.id)
+            put("jsonrpc", rpcRequest.jsonrpc)
+        }.toString()
+
+        val rpcDriver = Rpc20Driver(rpcUrl, object : HttpNetworkDriver {
+            override suspend fun makeHttpRequest(request: HttpRequest): String {
+                assertEquals(serializedRequest, request.body)
+                return ""
+            }
+        })
+
+        rpcDriver.makeRequest(rpcRequest)
+    }
 }
\ No newline at end of file