diff --git a/src/InputHandler.ts b/src/InputHandler.ts
index 8846b4be10..1b3907fd23 100644
--- a/src/InputHandler.ts
+++ b/src/InputHandler.ts
@@ -1291,7 +1291,9 @@ export class InputHandler extends Disposable implements IInputHandler {
           this._terminal.vt200Mouse = params[0] === 1000;
           this._terminal.normalMouse = params[0] > 1000;
           this._terminal.mouseEvents = true;
-          this._terminal.element.classList.add('enable-mouse-events');
+          if (this._terminal.element) {
+            this._terminal.element.classList.add('enable-mouse-events');
+          }
           this._terminal.selectionManager.disable();
           this._terminal.log('Binding to mouse events.');
           break;
@@ -1479,7 +1481,9 @@ export class InputHandler extends Disposable implements IInputHandler {
           this._terminal.vt200Mouse = false;
           this._terminal.normalMouse = false;
           this._terminal.mouseEvents = false;
-          this._terminal.element.classList.remove('enable-mouse-events');
+          if (this._terminal.element) {
+            this._terminal.element.classList.remove('enable-mouse-events');
+          }
           this._terminal.selectionManager.enable();
           break;
         case 1004: // send focusin/focusout events
diff --git a/src/Terminal.ts b/src/Terminal.ts
index 8a5d96ba27..4ddd0431df 100644
--- a/src/Terminal.ts
+++ b/src/Terminal.ts
@@ -736,6 +736,8 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
     this.register(addDisposableDomListener(this._viewportElement, 'scroll', () => this.selectionManager.refresh()));
 
     this.mouseHelper = new MouseHelper(this.renderer);
+    // apply mouse event classes set by escape codes before terminal was attached
+    this.element.classList.toggle('enable-mouse-events', this.mouseEvents);
 
     if (this.options.screenReaderMode) {
       // Note that this must be done *after* the renderer is created in order to