diff --git a/flutter_ffi_plugin/example/native/sample_crate/src/lib.rs b/flutter_ffi_plugin/example/native/sample_crate/src/lib.rs
index 85927dbe..aab1573b 100755
--- a/flutter_ffi_plugin/example/native/sample_crate/src/lib.rs
+++ b/flutter_ffi_plugin/example/native/sample_crate/src/lib.rs
@@ -18,8 +18,8 @@ pub fn get_hardward_id() -> Result<String> {
     Ok(hwid)
 }
 #[cfg(not(any(target_os = "windows", target_os = "macos", target_os = "linux")))]
-pub fn get_hardward_id() -> Option<String> {
-    None
+pub fn get_hardward_id() -> Result<String> {
+    Ok(String::from("UNSUPPORTED"))
 }
 
 // `chrono` supports all platforms, including web.