diff --git a/src/command_handler.rs b/src/command_handler.rs
index cd15c83..e5032e0 100644
--- a/src/command_handler.rs
+++ b/src/command_handler.rs
@@ -386,7 +386,7 @@ impl Handler {
         if !fan_ctrl.fan_available() {
             send_line(
                 socket,
-                b"{ \"warning\": \"this thermostat doesn't have fan!\" }",
+                b"{ \"warning\": \"this thermostat doesn't have a fan!\" }",
             );
             return Ok(Handler::Handled);
         }