diff --git a/src/core_api.rs b/src/core_api.rs
index e45dbd4..69e8686 100644
--- a/src/core_api.rs
+++ b/src/core_api.rs
@@ -41,7 +41,7 @@ pub enum MpvCommand {
         to: usize,
     },
     Observe {
-        id: isize,
+        id: usize,
         property: String,
     },
     PlaylistNext,
@@ -59,7 +59,7 @@ pub enum MpvCommand {
         option: SeekOptions,
     },
     Stop,
-    Unobserve(isize),
+    Unobserve(usize),
 }
 
 /// Helper trait to keep track of the string literals that mpv expects.
diff --git a/src/highlevel_api_extension.rs b/src/highlevel_api_extension.rs
index d6df375..61056b7 100644
--- a/src/highlevel_api_extension.rs
+++ b/src/highlevel_api_extension.rs
@@ -68,8 +68,8 @@ pub trait MpvExt {
     async fn restart(&self) -> Result<(), MpvError>;
     async fn prev(&self) -> Result<(), MpvError>;
     async fn pause(&self) -> Result<(), MpvError>;
-    async fn unobserve_property(&self, id: isize) -> Result<(), MpvError>;
-    async fn observe_property(&self, id: isize, property: &str) -> Result<(), MpvError>;
+    async fn unobserve_property(&self, id: usize) -> Result<(), MpvError>;
+    async fn observe_property(&self, id: usize, property: &str) -> Result<(), MpvError>;
     async fn next(&self) -> Result<(), MpvError>;
     async fn kill(&self) -> Result<(), MpvError>;
     async fn get_playlist(&self) -> Result<Playlist, MpvError>;
@@ -95,7 +95,7 @@ impl MpvExt for Mpv {
         self.run_command(MpvCommand::PlaylistNext).await
     }
 
-    async fn observe_property(&self, id: isize, property: &str) -> Result<(), MpvError> {
+    async fn observe_property(&self, id: usize, property: &str) -> Result<(), MpvError> {
         self.run_command(MpvCommand::Observe {
             id,
             property: property.to_string(),
@@ -103,7 +103,7 @@ impl MpvExt for Mpv {
         .await
     }
 
-    async fn unobserve_property(&self, id: isize) -> Result<(), MpvError> {
+    async fn unobserve_property(&self, id: usize) -> Result<(), MpvError> {
         self.run_command(MpvCommand::Unobserve(id)).await
     }
 
diff --git a/src/ipc.rs b/src/ipc.rs
index e269c7f..8531639 100644
--- a/src/ipc.rs
+++ b/src/ipc.rs
@@ -24,8 +24,8 @@ pub(crate) enum MpvIpcCommand {
     Command(Vec<String>),
     GetProperty(String),
     SetProperty(String, Value),
-    ObserveProperty(isize, String),
-    UnobserveProperty(isize),
+    ObserveProperty(usize, String),
+    UnobserveProperty(usize),
     Exit,
 }
 
@@ -114,7 +114,7 @@ impl MpvIpc {
 
     pub(crate) async fn observe_property(
         &mut self,
-        id: isize,
+        id: usize,
         property: &str,
     ) -> Result<Option<Value>, MpvError> {
         self.send_command(&[json!("observe_property"), json!(id), json!(property)])
@@ -123,7 +123,7 @@ impl MpvIpc {
 
     pub(crate) async fn unobserve_property(
         &mut self,
-        id: isize,
+        id: usize,
     ) -> Result<Option<Value>, MpvError> {
         self.send_command(&[json!("unobserve_property"), json!(id)])
             .await