diff --git a/src/public/Terminal.ts b/src/public/Terminal.ts
index d05a4f1007..70ce7db4de 100644
--- a/src/public/Terminal.ts
+++ b/src/public/Terminal.ts
@@ -30,7 +30,7 @@ export class Terminal implements ITerminalApi {
   public get textarea(): HTMLTextAreaElement { return this._core.textarea; }
   public get rows(): number { return this._core.rows; }
   public get cols(): number { return this._core.cols; }
-  public get markers(): IMarker[] { return this._core.markers; }
+  public get markers(): ReadonlyArray<IMarker> { return this._core.markers; }
   public blur(): void {
     this._core.blur();
   }
diff --git a/typings/xterm.d.ts b/typings/xterm.d.ts
index 24a30b256c..b6d1e32074 100644
--- a/typings/xterm.d.ts
+++ b/typings/xterm.d.ts
@@ -359,7 +359,7 @@ declare module 'xterm' {
      * (EXPERIMENTAL) Get all markers registered against the buffer. If the alt
      * buffer is active this will always return [].
      */
-    readonly markers: IMarker[];
+    readonly markers: ReadonlyArray<IMarker>;
 
     /**
      * Natural language strings that can be localized.