diff --git a/src/lib_rpc_http/RPC_server.ml b/src/lib_rpc_http/RPC_server.ml
index aa5fb8bcec9ce06fe5882f87f6f7c437334667b6..26d4e7a187732e51fe1d24ca53ec2325954ffed2 100644
--- a/src/lib_rpc_http/RPC_server.ml
+++ b/src/lib_rpc_http/RPC_server.ml
@@ -53,10 +53,21 @@ module RPC_logging = struct
   let rpc_http_event_error = rpc_http_event "rpc_http_event_error" Error
 
   let emit_async event fmt =
-    Format.kasprintf (fun message -> Lwt.ignore_result (emit event message)) fmt
+    Format.kasprintf
+      (fun message ->
+        Lwt.ignore_result
+          (emit
+             event
+             (Printf.sprintf "[pid:%d][resto] %s" (Unix.getpid ()) message)))
+      fmt
 
   let emit_lwt event fmt =
-    Format.kasprintf (fun message -> emit event message) fmt
+    Format.kasprintf
+      (fun message ->
+        emit
+          event
+          (Printf.sprintf "[pid:%d][resto] %s" (Unix.getpid ()) message))
+      fmt
 
   let debug f = emit_async rpc_http_event_debug f