diff --git a/beacon_node/execution_layer/src/engine_api.rs b/beacon_node/execution_layer/src/engine_api.rs
index 84b5b6c8b3..e678c70e8c 100644
--- a/beacon_node/execution_layer/src/engine_api.rs
+++ b/beacon_node/execution_layer/src/engine_api.rs
@@ -13,6 +13,7 @@ pub enum Error {
     BadResponse(String),
     RequestFailed(String),
     JsonRpc(RpcError),
+    Json(serde_json::Error),
 }
 
 impl From<reqwest::Error> for Error {
@@ -21,6 +22,12 @@ impl From<reqwest::Error> for Error {
     }
 }
 
+impl From<serde_json::Error> for Error {
+    fn from(e: serde_json::Error) -> Self {
+        Error::Json(e)
+    }
+}
+
 #[async_trait]
 pub trait EngineApi {
     async fn upcheck(&self) -> Result<(), Error>;
diff --git a/beacon_node/execution_layer/src/engine_api/http.rs b/beacon_node/execution_layer/src/engine_api/http.rs
index 6ba1bd1dbb..78323c8731 100644
--- a/beacon_node/execution_layer/src/engine_api/http.rs
+++ b/beacon_node/execution_layer/src/engine_api/http.rs
@@ -1,6 +1,6 @@
 use super::*;
 use async_trait::async_trait;
-use eth1::http::{hex_to_u64_be, response_result_or_error, send_rpc_request};
+use eth1::http::{response_result_or_error, send_rpc_request};
 pub use reqwest::Client;
 use sensitive_url::SensitiveUrl;
 use serde::{Deserialize, Serialize};
@@ -54,11 +54,9 @@ impl EngineApi for HttpJsonRpc {
         .map_err(Error::RequestFailed)?;
 
         let result = response_result_or_error(&response_body).map_err(Error::JsonRpc)?;
-        let string = result
-            .as_str()
-            .ok_or(Error::BadResponse("data was not string".to_string()))?;
+        let response: PreparePayloadResponse = serde_json::from_value(result)?;
 
-        hex_to_u64_be(string).map_err(Error::BadResponse)
+        Ok(response.payload_id)
     }
 }
 
@@ -71,3 +69,10 @@ struct PreparePayloadRequest {
     random: Hash256,
     fee_recipient: Address,
 }
+
+#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[serde(transparent, rename = "camelCase")]
+struct PreparePayloadResponse {
+    #[serde(with = "eth2_serde_utils::u64_hex_be")]
+    payload_id: u64,
+}