diff --git a/packages/common/http/test/xsrf_spec.ts b/packages/common/http/test/xsrf_spec.ts
index 36ba12bdf9..02a1569b07 100644
--- a/packages/common/http/test/xsrf_spec.ts
+++ b/packages/common/http/test/xsrf_spec.ts
@@ -8,12 +8,12 @@
 
 import {HttpHeaders} from '../src/headers';
 import {HttpRequest} from '../src/request';
-import {HttpXsrfCookieExtractor, HttpXsrfInterceptor} from '../src/xsrf';
+import {HttpXsrfCookieExtractor, HttpXsrfInterceptor, HttpXsrfTokenExtractor} from '../src/xsrf';
 
 import {HttpClientTestingBackend} from '../testing/src/backend';
 
-class SampleTokenExtractor {
-  constructor(private token: string|null) {}
+class SampleTokenExtractor extends HttpXsrfTokenExtractor {
+  constructor(private token: string|null) { super(); }
 
   getToken(): string|null { return this.token; }
 }