diff --git a/src/browser/Terminal.ts b/src/browser/Terminal.ts
index f1c799f2..0e030c1f 100644
--- a/src/browser/Terminal.ts
+++ b/src/browser/Terminal.ts
@@ -1008,7 +1008,7 @@ export class Terminal extends CoreTerminal implements ITerminal {
     if (this.buffer !== this.buffers.normal) {
       return undefined;
     }
-    return this.decorationService!.registerDecoration(decorationOptions);
+    return this.decorationService.registerDecoration(decorationOptions);
   }
 
   /**