diff --git a/kotlin-native/samples/nonBlockingEchoServer/src/nonBlockingEchoServerMain/kotlin/EchoServer.kt b/kotlin-native/samples/nonBlockingEchoServer/src/nonBlockingEchoServerMain/kotlin/EchoServer.kt
index ae31d0b31ad..b53b3528c5b 100644
--- a/kotlin-native/samples/nonBlockingEchoServer/src/nonBlockingEchoServerMain/kotlin/EchoServer.kt
+++ b/kotlin-native/samples/nonBlockingEchoServer/src/nonBlockingEchoServerMain/kotlin/EchoServer.kt
@@ -177,6 +177,7 @@ fun acceptClientsAndRun(serverFd: Int, block: suspend Client.() -> Unit) {
                                 waitingFor.continuation.resumeWithException(IOException(getUnixError()))
                             waitingFor.continuation.resume(Unit)
                         }
+                        else -> throw Error("No operation for $waitingFor is defined")
                     }
                 }
             }