diff --git a/src/TestUtils.test.ts b/src/TestUtils.test.ts
index 109bebd2f..3f53c7d3a 100644
--- a/src/TestUtils.test.ts
+++ b/src/TestUtils.test.ts
@@ -9,7 +9,7 @@ import { IBufferLine, ICellData, IAttributeData } from './core/Types';
 import { ICircularList, XtermListener } from './common/Types';
 import { Buffer } from './Buffer';
 import * as Browser from './common/Platform';
-import { ITheme, IDisposable, IMarker, IEvent, ITerminalAddon, ISelectionPosition } from 'xterm';
+import { ITheme, IDisposable, IMarker, IEvent, ISelectionPosition } from 'xterm';
 import { Terminal } from './Terminal';
 import { AttributeData } from './core/buffer/BufferLine';
 
@@ -30,9 +30,6 @@ export class MockTerminal implements ITerminal {
   onKey: IEvent<{ key: string; domEvent: KeyboardEvent; }>;
   onRender: IEvent<{ start: number; end: number; }>;
   onResize: IEvent<{ cols: number; rows: number; }>;
-  loadAddon(addon: ITerminalAddon): void {
-    throw new Error('Method not implemented.');
-  }
   markers: IMarker[];
   addMarker(cursorYOffset: number): IMarker {
     throw new Error('Method not implemented.');
diff --git a/src/Types.ts b/src/Types.ts
index 6136dafbb..4ffcf7e84 100644
--- a/src/Types.ts
+++ b/src/Types.ts
@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { ITerminalOptions as IPublicTerminalOptions, IEventEmitter, IDisposable, IMarker, Terminal, ISelectionPosition } from 'xterm';
+import { ITerminalOptions as IPublicTerminalOptions, IEventEmitter, IDisposable, IMarker, ISelectionPosition } from 'xterm';
 import { IColorSet, IRenderer } from './renderer/Types';
 import { ICharset, IAttributeData, ICellData, IBufferLine, CharData } from './core/Types';
 import { ICircularList } from './common/Types';
@@ -271,10 +271,6 @@ export interface IPublicTerminal extends IDisposable, IEventEmitter {
   reset(): void;
 }
 
-export interface ITerminalAddon extends IDisposable {
-  activate(terminal: Terminal): void;
-}
-
 export interface IBufferAccessor {
   buffer: IBuffer;
 }
diff --git a/typings/xterm.d.ts b/typings/xterm.d.ts
index 89d2b62b4..c059b480a 100644
--- a/typings/xterm.d.ts
+++ b/typings/xterm.d.ts
@@ -884,6 +884,9 @@ declare module 'xterm' {
     loadAddon(addon: ITerminalAddon): void;
   }
 
+  /**
+   * An addon that can provide additional functionality to the terminal.
+   */
   export interface ITerminalAddon extends IDisposable {
     /**
      * (EXPERIMENTAL) This is called when the addon is activated within xterm.js.