diff --git a/ports/servoshell/prefs.rs b/ports/servoshell/prefs.rs
index 7eae7a3850c..306aaa197d2 100644
--- a/ports/servoshell/prefs.rs
+++ b/ports/servoshell/prefs.rs
@@ -653,6 +653,10 @@ pub(crate) fn parse_command_line_arguments(args: Vec<String>) -> ArgumentParsing
         preferences.media_glvideo_enabled = false;
     }
 
+    if let Some(user_agent) = opt_match.opt_str("user-agent") {
+        preferences.user_agent = user_agent;
+    }
+
     let opts = Opts {
         debug: debug_options.clone(),
         wait_for_stable_image,