diff --git a/src/roma/byob/dispatcher/dispatcher.cc b/src/roma/byob/dispatcher/dispatcher.cc
index bfd5aa47..b6a8e59b 100644
--- a/src/roma/byob/dispatcher/dispatcher.cc
+++ b/src/roma/byob/dispatcher/dispatcher.cc
@@ -84,12 +84,16 @@ absl::Status Dispatcher::Init(const int listen_fd) {
 
 absl::StatusOr<std::string> Dispatcher::LoadBinary(
     std::filesystem::path binary_path, const int n_workers) {
+  if (n_workers <= 0) {
+    return absl::InvalidArgumentError(
+        absl::StrCat("`n_workers=", n_workers, "` must be positive"));
+  }
   std::string code_token = ToString(Uuid::GenerateUuid());
   LoadRequest payload;
   {
     std::ifstream ifs(std::move(binary_path), std::ios::binary);
     if (!ifs.is_open()) {
-      return absl::InvalidArgumentError(
+      return absl::UnavailableError(
           absl::StrCat("Cannot open ", binary_path.native()));
     }
     payload.set_binary_content(std::string(std::istreambuf_iterator<char>(ifs),
diff --git a/src/roma/byob/dispatcher/dispatcher_test.cc b/src/roma/byob/dispatcher/dispatcher_test.cc
index da5a0944..5b20d167 100644
--- a/src/roma/byob/dispatcher/dispatcher_test.cc
+++ b/src/roma/byob/dispatcher/dispatcher_test.cc
@@ -111,6 +111,28 @@ TEST(DispatcherTest, ShutdownDispatcherThenWorker) {
   worker.join();
 }
 
+TEST(DispatcherTest, LoadErrorsWhenNWorkersNonPositive) {
+  const int fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
+  ASSERT_NE(fd, -1);
+  BindAndListenOnPath(fd, "abcd.sock");
+  absl::Cleanup cleanup = [] { EXPECT_EQ(::unlink("abcd.sock"), 0); };
+  absl::Notification done;
+  std::thread worker([&done] {
+    const int fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
+    ASSERT_NE(fd, -1);
+    ConnectToPath(fd, "abcd.sock");
+    done.WaitForNotification();
+    EXPECT_EQ(::close(fd), 0);
+  });
+  Dispatcher dispatcher;
+  ASSERT_TRUE(dispatcher.Init(fd).ok());
+  const absl::StatusOr<std::string> code_token =
+      dispatcher.LoadBinary("src/roma/byob/udf/new_udf", /*n_workers=*/0);
+  EXPECT_FALSE(code_token.ok());
+  done.Notify();
+  worker.join();
+}
+
 TEST(DispatcherTest, LoadErrorsWhenFileDoesntExist) {
   const int fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
   ASSERT_NE(fd, -1);