diff --git a/src/cast/proxies.rs b/src/cast/proxies.rs
index b070170a5..1238ba907 100644
--- a/src/cast/proxies.rs
+++ b/src/cast/proxies.rs
@@ -29,7 +29,7 @@ pub mod media {
     #[derive(Serialize, Debug)]
     pub struct GetStatusRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -41,7 +41,7 @@ pub mod media {
     #[derive(Serialize, Debug)]
     pub struct MediaRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "sessionId")]
         pub session_id: String,
@@ -63,7 +63,7 @@ pub mod media {
     #[derive(Serialize, Debug)]
     pub struct PlaybackGenericRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "mediaSessionId")]
         pub media_session_id: i32,
@@ -78,7 +78,7 @@ pub mod media {
     #[derive(Serialize, Debug)]
     pub struct PlaybackSeekRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "mediaSessionId")]
         pub media_session_id: i32,
@@ -246,7 +246,7 @@ pub mod media {
     #[derive(Deserialize, Debug)]
     pub struct StatusReply {
         #[serde(rename = "requestId", default)]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -257,25 +257,25 @@ pub mod media {
     #[derive(Deserialize, Debug)]
     pub struct LoadCancelledReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
     }
 
     #[derive(Deserialize, Debug)]
     pub struct LoadFailedReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
     }
 
     #[derive(Deserialize, Debug)]
     pub struct InvalidPlayerStateReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
     }
 
     #[derive(Deserialize, Debug)]
     pub struct InvalidRequestReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -293,7 +293,7 @@ pub mod receiver {
     #[derive(Serialize, Debug)]
     pub struct AppLaunchRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -305,7 +305,7 @@ pub mod receiver {
     #[derive(Serialize, Debug)]
     pub struct AppStopRequest<'a> {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -317,7 +317,7 @@ pub mod receiver {
     #[derive(Serialize, Debug)]
     pub struct GetStatusRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -326,7 +326,7 @@ pub mod receiver {
     #[derive(Serialize, Debug)]
     pub struct SetVolumeRequest {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -337,7 +337,7 @@ pub mod receiver {
     #[derive(Deserialize, Debug)]
     pub struct StatusReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -398,7 +398,7 @@ pub mod receiver {
     #[derive(Deserialize, Debug)]
     pub struct LaunchErrorReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
@@ -409,7 +409,7 @@ pub mod receiver {
     #[derive(Deserialize, Debug)]
     pub struct InvalidRequestReply {
         #[serde(rename = "requestId")]
-        pub request_id: i32,
+        pub request_id: u32,
 
         #[serde(rename = "type")]
         pub typ: String,
diff --git a/src/channels/media.rs b/src/channels/media.rs
index 8dd727b89..a4671c71f 100644
--- a/src/channels/media.rs
+++ b/src/channels/media.rs
@@ -322,7 +322,7 @@ pub struct Media {
 #[derive(Clone, Debug)]
 pub struct Status {
     /// Unique id of the request that requested the status.
-    pub request_id: i32,
+    pub request_id: u32,
     /// Detailed status of every media status entry.
     pub entries: Vec<StatusEntry>,
 }
@@ -369,28 +369,28 @@ pub struct StatusEntry {
 #[derive(Copy, Clone, Debug)]
 pub struct LoadCancelled {
     /// Unique id of the request that caused this error.
-    pub request_id: i32,
+    pub request_id: u32,
 }
 
 /// Describes the load failed error.
 #[derive(Copy, Clone, Debug)]
 pub struct LoadFailed {
     /// Unique id of the request that caused this error.
-    pub request_id: i32,
+    pub request_id: u32,
 }
 
 /// Describes the invalid player state error.
 #[derive(Copy, Clone, Debug)]
 pub struct InvalidPlayerState {
     /// Unique id of the request that caused this error.
-    pub request_id: i32,
+    pub request_id: u32,
 }
 
 /// Describes the invalid request error.
 #[derive(Clone, Debug)]
 pub struct InvalidRequest {
     /// Unique id of the invalid request.
-    pub request_id: i32,
+    pub request_id: u32,
     /// Description of the invalid request reason if available.
     pub reason: Option<String>,
 }
@@ -455,7 +455,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::media::GetStatusRequest {
             typ: MESSAGE_TYPE_GET_STATUS.to_string(),
@@ -510,7 +510,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let metadata = media.metadata.as_ref().map(|m| match *m {
             Metadata::Generic(ref x) => proxies::media::Metadata {
@@ -666,7 +666,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::media::PlaybackGenericRequest {
             request_id,
@@ -700,7 +700,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::media::PlaybackGenericRequest {
             request_id,
@@ -735,7 +735,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::media::PlaybackGenericRequest {
             request_id,
@@ -778,7 +778,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::media::PlaybackSeekRequest {
             request_id,
@@ -905,7 +905,7 @@ where
     /// Returned `Result` should consist of either `Status` instance or an `Error`.
     fn receive_status_entry(
         &self,
-        request_id: i32,
+        request_id: u32,
         media_session_id: i32,
     ) -> Result<StatusEntry, Error> {
         self.message_manager.receive_find_map(|message| {
diff --git a/src/channels/receiver.rs b/src/channels/receiver.rs
index c9fb018fb..3984b317e 100644
--- a/src/channels/receiver.rs
+++ b/src/channels/receiver.rs
@@ -91,7 +91,7 @@ pub struct Application {
 #[derive(Clone, Debug)]
 pub struct Status {
     /// Unique id of the request that requested the status.
-    pub request_id: i32,
+    pub request_id: u32,
     /// Contains the list of applications that are currently run.
     pub applications: Vec<Application>,
     /// Determines whether the Cast device is the active input or not.
@@ -106,7 +106,7 @@ pub struct Status {
 #[derive(Clone, Debug)]
 pub struct LaunchError {
     /// Unique id of the request that tried to launch application.
-    pub request_id: i32,
+    pub request_id: u32,
     /// Description of the launch error reason if available.
     pub reason: Option<String>,
 }
@@ -115,7 +115,7 @@ pub struct LaunchError {
 #[derive(Clone, Debug)]
 pub struct InvalidRequest {
     /// Unique id of the invalid request.
-    pub request_id: i32,
+    pub request_id: u32,
     /// Description of the invalid request reason if available.
     pub reason: Option<String>,
 }
@@ -212,7 +212,7 @@ where
     ///
     /// * `app` - `CastDeviceApp` instance reference to run.
     pub fn launch_app(&self, app: &CastDeviceApp) -> Result<Application, Error> {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::receiver::AppLaunchRequest {
             typ: MESSAGE_TYPE_LAUNCH.to_string(),
@@ -301,7 +301,7 @@ where
     where
         S: Into<Cow<'a, str>>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::receiver::AppStopRequest {
             typ: MESSAGE_TYPE_STOP.to_string(),
@@ -350,7 +350,7 @@ where
     ///
     /// Returned `Result` should consist of either `Status` instance or an `Error`.
     pub fn get_status(&self) -> Result<Status, Error> {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
 
         let payload = serde_json::to_string(&proxies::receiver::GetStatusRequest {
             typ: MESSAGE_TYPE_GET_STATUS.to_string(),
@@ -398,7 +398,7 @@ where
     where
         T: Into<Volume>,
     {
-        let request_id = self.message_manager.generate_request_id();
+        let request_id = self.message_manager.generate_request_id().get();
         let volume = volume.into();
 
         let payload = serde_json::to_string(&proxies::receiver::SetVolumeRequest {
diff --git a/src/message_manager.rs b/src/message_manager.rs
index c2f42cd61..f51f1d15d 100644
--- a/src/message_manager.rs
+++ b/src/message_manager.rs
@@ -1,5 +1,6 @@
 use std::{
     io::{Read, Write},
+    num::NonZeroU32,
     ops::{Deref, DerefMut},
 };
 
@@ -60,16 +61,6 @@ impl<T> Lock<T> {
         })
     }
 
-    fn borrow(&self) -> LockGuard<'_, T> {
-        LockGuard({
-            #[cfg(feature = "thread_safe")]
-            let guard = self.0.lock().unwrap();
-            #[cfg(not(feature = "thread_safe"))]
-            let guard = self.0.borrow();
-            guard
-        })
-    }
-
     fn borrow_mut(&self) -> LockGuardMut<'_, T> {
         LockGuardMut({
             #[cfg(feature = "thread_safe")]
@@ -112,7 +103,7 @@ where
 {
     message_buffer: Lock<Vec<CastMessage>>,
     stream: Lock<S>,
-    request_counter: Lock<i32>,
+    request_counter: Lock<NonZeroU32>,
 }
 
 impl<S> MessageManager<S>
@@ -123,7 +114,7 @@ where
         MessageManager {
             stream: Lock::new(stream),
             message_buffer: Lock::new(vec![]),
-            request_counter: Lock::new(1),
+            request_counter: Lock::new(NonZeroU32::MIN),
         }
     }
 
@@ -248,11 +239,10 @@ where
     /// # Return value
     ///
     /// Unique (in the scope of this particular `MessageManager` instance) integer number.
-    pub fn generate_request_id(&self) -> i32 {
-        let request_id = *self.request_counter.borrow() + 1;
-
-        *self.request_counter.borrow_mut() = request_id;
-
+    pub fn generate_request_id(&self) -> NonZeroU32 {
+        let mut counter = self.request_counter.borrow_mut();
+        let request_id = *counter;
+        *counter = counter.checked_add(1).unwrap();
         request_id
     }