diff --git a/src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/WsConnectionImpl.kt b/src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/WsConnectionImpl.kt
index 6f0b0134..7d6315d1 100644
--- a/src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/WsConnectionImpl.kt
+++ b/src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/WsConnectionImpl.kt
@@ -259,7 +259,7 @@ open class WsConnectionImpl(
         val calls = rpcSend
             .asFlux()
             .map {
-                Unpooled.wrappedBuffer(Global.objectMapper.writeValueAsBytes(it))
+                Unpooled.wrappedBuffer(it.toJson())
             }
 
         return outbound.send(