diff --git a/helix-dap/src/client.rs b/helix-dap/src/client.rs
index 62557951..28cc7c90 100644
--- a/helix-dap/src/client.rs
+++ b/helix-dap/src/client.rs
@@ -1,7 +1,7 @@
 use crate::{
     transport::{Payload, Request, Transport},
     types::*,
-    Error, Result,
+    Error, Result, ThreadId,
 };
 use helix_core::syntax::DebuggerQuirks;
 
@@ -30,9 +30,9 @@ pub struct Client {
     request_counter: AtomicU64,
     pub caps: Option<DebuggerCapabilities>,
     // thread_id -> frames
-    pub stack_frames: HashMap<isize, Vec<StackFrame>>,
-    pub thread_states: HashMap<isize, String>,
-    pub thread_id: Option<isize>,
+    pub stack_frames: HashMap<ThreadId, Vec<StackFrame>>,
+    pub thread_states: HashMap<ThreadId, String>,
+    pub thread_id: Option<ThreadId>,
     /// Currently active frame for the current thread.
     pub active_frame: Option<usize>,
     pub breakpoints: Vec<Breakpoint>,
@@ -311,7 +311,7 @@ impl Client {
         self.request::<requests::ConfigurationDone>(()).await
     }
 
-    pub async fn continue_thread(&mut self, thread_id: isize) -> Result<Option<bool>> {
+    pub async fn continue_thread(&mut self, thread_id: ThreadId) -> Result<Option<bool>> {
         let args = requests::ContinueArguments { thread_id };
 
         let response = self.request::<requests::Continue>(args).await?;
@@ -320,7 +320,7 @@ impl Client {
 
     pub async fn stack_trace(
         &mut self,
-        thread_id: isize,
+        thread_id: ThreadId,
     ) -> Result<(Vec<StackFrame>, Option<usize>)> {
         let args = requests::StackTraceArguments {
             thread_id,
@@ -358,7 +358,7 @@ impl Client {
         Ok(response.variables)
     }
 
-    pub async fn step_in(&mut self, thread_id: isize) -> Result<()> {
+    pub async fn step_in(&mut self, thread_id: ThreadId) -> Result<()> {
         let args = requests::StepInArguments {
             thread_id,
             target_id: None,
@@ -368,7 +368,7 @@ impl Client {
         self.request::<requests::StepIn>(args).await
     }
 
-    pub async fn step_out(&mut self, thread_id: isize) -> Result<()> {
+    pub async fn step_out(&mut self, thread_id: ThreadId) -> Result<()> {
         let args = requests::StepOutArguments {
             thread_id,
             granularity: None,
@@ -377,7 +377,7 @@ impl Client {
         self.request::<requests::StepOut>(args).await
     }
 
-    pub async fn next(&mut self, thread_id: isize) -> Result<()> {
+    pub async fn next(&mut self, thread_id: ThreadId) -> Result<()> {
         let args = requests::NextArguments {
             thread_id,
             granularity: None,
@@ -386,7 +386,7 @@ impl Client {
         self.request::<requests::Next>(args).await
     }
 
-    pub async fn pause(&mut self, thread_id: isize) -> Result<()> {
+    pub async fn pause(&mut self, thread_id: ThreadId) -> Result<()> {
         let args = requests::PauseArguments { thread_id };
 
         self.request::<requests::Pause>(args).await
diff --git a/helix-dap/src/types.rs b/helix-dap/src/types.rs
index 5430771f..c2becf33 100644
--- a/helix-dap/src/types.rs
+++ b/helix-dap/src/types.rs
@@ -2,6 +2,17 @@ use serde::{Deserialize, Serialize};
 use serde_json::Value;
 use std::path::PathBuf;
 
+#[derive(
+    Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Deserialize, Serialize,
+)]
+pub struct ThreadId(isize);
+
+impl std::fmt::Display for ThreadId {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
 pub trait Request {
     type Arguments: serde::de::DeserializeOwned + serde::Serialize;
     type Result: serde::de::DeserializeOwned + serde::Serialize;
@@ -157,7 +168,7 @@ pub struct StackFrame {
 #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
 pub struct Thread {
-    pub id: isize,
+    pub id: ThreadId,
     pub name: String,
 }
 
@@ -317,7 +328,7 @@ pub mod requests {
     #[derive(Debug, Default, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct ContinueArguments {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
     }
 
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
@@ -338,7 +349,7 @@ pub mod requests {
     #[derive(Debug, Default, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct StackTraceArguments {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
         pub start_frame: Option<usize>,
         pub levels: Option<usize>,
         pub format: Option<StackFrameFormat>,
@@ -424,7 +435,7 @@ pub mod requests {
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct StepInArguments {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
         pub target_id: Option<usize>,
         pub granularity: Option<String>,
     }
@@ -441,7 +452,7 @@ pub mod requests {
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct StepOutArguments {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
         pub granularity: Option<String>,
     }
 
@@ -457,7 +468,7 @@ pub mod requests {
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct NextArguments {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
         pub granularity: Option<String>,
     }
 
@@ -473,7 +484,7 @@ pub mod requests {
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct PauseArguments {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
     }
 
     #[derive(Debug)]
@@ -574,7 +585,7 @@ pub mod events {
     pub struct Stopped {
         pub reason: String,
         pub description: Option<String>,
-        pub thread_id: Option<isize>,
+        pub thread_id: Option<ThreadId>,
         pub preserve_focus_hint: Option<bool>,
         pub text: Option<String>,
         pub all_threads_stopped: Option<bool>,
@@ -584,7 +595,7 @@ pub mod events {
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
     #[serde(rename_all = "camelCase")]
     pub struct Continued {
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
         pub all_threads_continued: Option<bool>,
     }
 
@@ -604,7 +615,7 @@ pub mod events {
     #[serde(rename_all = "camelCase")]
     pub struct Thread {
         pub reason: String,
-        pub thread_id: isize,
+        pub thread_id: ThreadId,
     }
 
     #[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
@@ -661,7 +672,7 @@ pub mod events {
     // #[serde(rename_all = "camelCase")]
     // pub struct Invalidated {
     // pub areas: Vec<InvalidatedArea>,
-    // pub thread_id: Option<usize>,
+    // pub thread_id: Option<ThreadId>,
     // pub stack_frame_id: Option<usize>,
     // }
 
diff --git a/helix-term/src/application.rs b/helix-term/src/application.rs
index d8ff2a8a..27062a36 100644
--- a/helix-term/src/application.rs
+++ b/helix-term/src/application.rs
@@ -320,7 +320,12 @@ impl Application {
                             for thread in threads {
                                 fetch_stack_trace(debugger, thread.id).await;
                             }
-                            select_thread_id(&mut self.editor, thread_id.unwrap_or(0), false).await;
+                            select_thread_id(
+                                &mut self.editor,
+                                thread_id.unwrap_or_default(),
+                                false,
+                            )
+                            .await;
                         }
                     } else if let Some(thread_id) = thread_id {
                         debugger.thread_states.insert(thread_id, reason.clone()); // TODO: dap uses "type" || "reason" here
diff --git a/helix-term/src/commands/dap.rs b/helix-term/src/commands/dap.rs
index a7cf7e81..6df9be22 100644
--- a/helix-term/src/commands/dap.rs
+++ b/helix-term/src/commands/dap.rs
@@ -6,7 +6,7 @@ use crate::{
     ui::{FilePicker, Prompt, PromptEvent},
 };
 use helix_core::{syntax::DebugConfigCompletion, Selection};
-use helix_dap::{self as dap, Client};
+use helix_dap::{self as dap, Client, ThreadId};
 use helix_lsp::block_on;
 
 use serde_json::{to_value, Value};
@@ -34,7 +34,7 @@ pub fn resume_application(debugger: &mut Client) {
     debugger.thread_id = None;
 }
 
-pub async fn select_thread_id(editor: &mut Editor, thread_id: isize, force: bool) {
+pub async fn select_thread_id(editor: &mut Editor, thread_id: ThreadId, force: bool) {
     let debugger = match &mut editor.debugger {
         Some(debugger) => debugger,
         None => return,
@@ -53,7 +53,7 @@ pub async fn select_thread_id(editor: &mut Editor, thread_id: isize, force: bool
     }
 }
 
-pub async fn fetch_stack_trace(debugger: &mut Client, thread_id: isize) {
+pub async fn fetch_stack_trace(debugger: &mut Client, thread_id: ThreadId) {
     let (frames, _) = match debugger.stack_trace(thread_id).await {
         Ok(frames) => frames,
         Err(_) => return,