diff --git a/packages/service-worker/worker/src/adapter.ts b/packages/service-worker/worker/src/adapter.ts
index 5955cdd56b..a8fb54058c 100644
--- a/packages/service-worker/worker/src/adapter.ts
+++ b/packages/service-worker/worker/src/adapter.ts
@@ -18,7 +18,7 @@ export class Adapter {
   constructor(scope: ServiceWorkerGlobalScope) {
     // Suffixing `ngsw` with the baseHref to avoid clash of cache names
     // for SWs with different scopes on the same domain.
-    const baseHref = new URL(scope.registration.scope).pathname;
+    const baseHref = this.parseUrl(scope.registration.scope).path;
     this.cacheNamePrefix = 'ngsw:' + baseHref;
   }
 
diff --git a/packages/service-worker/worker/testing/scope.ts b/packages/service-worker/worker/testing/scope.ts
index 20fedb6a95..5ce782c98a 100644
--- a/packages/service-worker/worker/testing/scope.ts
+++ b/packages/service-worker/worker/testing/scope.ts
@@ -116,9 +116,9 @@ export class SwTestHarness implements ServiceWorkerGlobalScope, Adapter, Context
 
   constructor(
       private server: MockServerState, readonly caches: MockCacheStorage, private origin: string) {
-    this.time = Date.now();
-    const baseHref = new URL(this.registration.scope).pathname;
+    const baseHref = this.parseUrl(origin).path;
     this.cacheNamePrefix = 'ngsw:' + baseHref;
+    this.time = Date.now();
   }
 
   async resolveSelfMessages(): Promise<void> {