diff --git a/src/harness/unittests/tsserverProjectSystem.ts b/src/harness/unittests/tsserverProjectSystem.ts
index 2c5d4c59bab..b7536248d36 100644
--- a/src/harness/unittests/tsserverProjectSystem.ts
+++ b/src/harness/unittests/tsserverProjectSystem.ts
@@ -243,11 +243,9 @@ namespace ts.projectSystem {
         }
     }
 
-    export function createSession(host: TestServerHost, opts: Partial<server.SessionOptions> = {}) {
+    export function createSession(host: server.ServerHost, opts: Partial<server.SessionOptions> = {}) {
         if (opts.typingsInstaller === undefined) {
-            const globalTypingsCacheLocation = "/a/data";
-            host.ensureFileOrFolder({ path: globalTypingsCacheLocation });
-            opts.typingsInstaller = new TestTypingsInstaller(globalTypingsCacheLocation, /*throttleLimit*/ 5, host);
+            opts.typingsInstaller = new TestTypingsInstaller("/a/data", /*throttleLimit*/ 5, host);
         }
 
         if (opts.eventHandler !== undefined) {
diff --git a/src/harness/unittests/typingsInstaller.ts b/src/harness/unittests/typingsInstaller.ts
index cf3d82ca3d7..1e0a66f6d55 100644
--- a/src/harness/unittests/typingsInstaller.ts
+++ b/src/harness/unittests/typingsInstaller.ts
@@ -34,8 +34,7 @@ namespace ts.projectSystem {
     }
 
     class Installer extends TestTypingsInstaller {
-        constructor(host: TestServerHost, p?: InstallerParams, log?: TI.Log) {
-            host.ensureFileOrFolder({ path: (p && p.globalTypingsCacheLocation) || "/a/data" });
+        constructor(host: server.ServerHost, p?: InstallerParams, log?: TI.Log) {
             super(
                 (p && p.globalTypingsCacheLocation) || "/a/data",
                 (p && p.throttleLimit) || 5,