diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index d7bd8f85a1b..eb5a9e3f9e4 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -481,12 +481,12 @@ impl UserAgentPlatform {
                 const ARCHITECTURE: &str = "";
 
                 format!(
-                    "Mozilla/5.0 (Windows NT 10.0; Win64; {ARCHITECTURE}rv:128.0) Servo/{SERVO_VERSION} Firefox/128.0"
+                    "Mozilla/5.0 (Windows NT 10.0; Win64; {ARCHITECTURE}rv:140.0) Servo/{SERVO_VERSION} Firefox/140.0"
                 )
             },
             UserAgentPlatform::Desktop if cfg!(target_os = "macos") => {
                 format!(
-                    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:128.0) Servo/{SERVO_VERSION} Firefox/128.0"
+                    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:140.0) Servo/{SERVO_VERSION} Firefox/140.0"
                 )
             },
             UserAgentPlatform::Desktop => {
@@ -497,19 +497,19 @@ impl UserAgentPlatform {
                 const ARCHITECTURE: &str = "i686";
 
                 format!(
-                    "Mozilla/5.0 (X11; Linux {ARCHITECTURE}; rv:128.0) Servo/{SERVO_VERSION} Firefox/128.0"
+                    "Mozilla/5.0 (X11; Linux {ARCHITECTURE}; rv:140.0) Servo/{SERVO_VERSION} Firefox/140.0"
                 )
             },
             UserAgentPlatform::Android => {
                 format!(
-                    "Mozilla/5.0 (Android 10; Mobile; rv:128.0) Servo/{SERVO_VERSION} Firefox/128.0"
+                    "Mozilla/5.0 (Android 10; Mobile; rv:140.0) Servo/{SERVO_VERSION} Firefox/140.0"
                 )
             },
             UserAgentPlatform::OpenHarmony => format!(
-                "Mozilla/5.0 (OpenHarmony; Mobile; rv:128.0) Servo/{SERVO_VERSION} Firefox/128.0"
+                "Mozilla/5.0 (OpenHarmony; Mobile; rv:140.0) Servo/{SERVO_VERSION} Firefox/140.0"
             ),
             UserAgentPlatform::Ios => format!(
-                "Mozilla/5.0 (iPhone; CPU iPhone OS 18_0 like Mac OS X; rv:128.0) Servo/{SERVO_VERSION} Firefox/128.0"
+                "Mozilla/5.0 (iPhone; CPU iPhone OS 18_6 like Mac OS X; rv:140.0) Servo/{SERVO_VERSION} Firefox/140.0"
             ),
         }
     }