diff --git a/addons/xterm-addon-attach/README.md b/addons/xterm-addon-attach/README.md
index 2040455c..67ebf17b 100644
--- a/addons/xterm-addon-attach/README.md
+++ b/addons/xterm-addon-attach/README.md
@@ -12,7 +12,7 @@ npm install --save xterm-addon-attach
 
 ```ts
 import { Terminal } from 'xterm';
-import { FitAddon } from 'xterm-addon-attach';
+import { AttachAddon } from 'xterm-addon-attach';
 
 const terminal = new Terminal();
 const attachAddon = new AttachAddon(webSocket);
diff --git a/src/Terminal.ts b/src/Terminal.ts
index 53d8fe3c..63400bcb 100644
--- a/src/Terminal.ts
+++ b/src/Terminal.ts
@@ -572,8 +572,8 @@ export class Terminal extends Disposable implements ITerminal, IDisposable, IInp
     // Performance: Add viewport and helper elements from the fragment
     this.element.appendChild(fragment);
 
-    this._theme = this.options.theme;
-    this.options.theme = null;
+    this._theme = this.options.theme || this._theme;
+    this.options.theme = undefined;
     this._colorManager = new ColorManager(document, this.options.allowTransparency);
     this._colorManager.setTheme(this._theme);