diff --git a/packages/server/src/rpc/RPCRouter.ts b/packages/server/src/rpc/RPCRouter.ts
index b78ff5a..ad6ad4a 100644
--- a/packages/server/src/rpc/RPCRouter.ts
+++ b/packages/server/src/rpc/RPCRouter.ts
@@ -1,4 +1,5 @@
-import { Context, Effect, Layer } from "effect"
+import { TRPCError } from "@trpc/server"
+import { Context, Data, Effect, Layer } from "effect"
 import { TRPCBuilder } from "../trpc/TRPCBuilder"
 import { RPCProcedureBuilder } from "./procedures/RPCProcedureBuilder"
 import { todoRouter } from "./routers/todo"
@@ -9,14 +10,26 @@ export const router = Effect.gen(function*() {
     const procedure = yield* RPCProcedureBuilder
 
     return t.router({
-        ping: procedure.query(({ ctx }) =>
-            ctx.run(Effect.succeed("pong"))
-        ),
+        ping: procedure.query(({ ctx }) => ctx.run(
+            Effect.succeed("pong")
+        )),
+
+        fail1: procedure.query(({ ctx }) => ctx.run(
+            Effect.fail(new AnError({ aValue: "A value" }))
+        )),
+        fail2: procedure.query(({ ctx }) => ctx.run(
+            Effect.fail(new TRPCError({ code: "NOT_IMPLEMENTED" }))
+        )),
 
         todo: yield* todoRouter,
     })
 })
 
+class AnError extends Data.TaggedError("AnError")<{
+    aValue: string
+}> {}
+
+
 export class RPCRouter extends Context.Tag("RPCRouter")<RPCRouter,
     Effect.Effect.Success<typeof router>
 >() {}