diff --git a/src/directLine.ts b/src/directLine.ts
index 39752b81d..e7ddcdaf8 100644
--- a/src/directLine.ts
+++ b/src/directLine.ts
@@ -22,6 +22,7 @@ import 'rxjs/add/observable/empty';
 import 'rxjs/add/observable/from';
 import 'rxjs/add/observable/interval';
 import 'rxjs/add/observable/of';
+import 'rxjs/add/observable/throw';
 
 // Direct Line 3.0 types