diff --git a/CHANGELOG.md b/CHANGELOG.md
index 908a1b0d4..ed284eb34 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## v6.0.3
+* [Upgrade typescript version to 3.5.2](https://github.com/TypeStrong/ts-loader/pull/954) (#954) - thanks @fa93hws
+
 ## v6.0.2
 * [Set configFilePath when reading config file](https://github.com/TypeStrong/ts-loader/pull/942) (#939) - thanks @konpikwastaken!
 
diff --git a/package.json b/package.json
index 184e92a4d..69a57801a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ts-loader",
-  "version": "6.0.2",
+  "version": "6.0.3",
   "description": "TypeScript loader for webpack",
   "main": "index.js",
   "types": "dist/types/index.d.ts",
@@ -88,7 +88,7 @@
     "rimraf": "^2.6.2",
     "tslint": "^5.11.0",
     "tslint-config-prettier": "^1.15.0",
-    "typescript": "^3.1.1",
+    "typescript": "^3.5.2",
     "webpack": "^4.5.0",
     "webpack-cli": "^3.1.1"
   },
diff --git a/src/servicesHost.ts b/src/servicesHost.ts
index f54e9d71c..6415bafa1 100644
--- a/src/servicesHost.ts
+++ b/src/servicesHost.ts
@@ -65,7 +65,8 @@ export function makeServicesHost(
     compiler.sys.fileExists(filePathToCheck) ||
     readFile(filePathToCheck) !== undefined;
 
-  const moduleResolutionHost: ModuleResolutionHost = {
+  let clearCache: Action | null = null;
+  let moduleResolutionHost: ModuleResolutionHost = {
     fileExists,
     readFile: readFileWithFallback,
     realpath: compiler.sys.realpath,
@@ -74,7 +75,11 @@ export function makeServicesHost(
     getDirectories: compiler.sys.getDirectories
   };
 
-  const clearCache = enableFileCaching ? addCache(moduleResolutionHost) : null;
+  if (enableFileCaching) {
+    const cached = addCache(moduleResolutionHost);
+    clearCache = cached.clearCache;
+    moduleResolutionHost = cached.moduleResolutionHost;
+  }
 
   // loader.context seems to work fine on Linux / Mac regardless causes problems for @types resolution on Windows for TypeScript < 2.3
   const getCurrentDirectory = () => loader.context;
@@ -651,42 +656,29 @@ function populateDependencyGraphs(
   });
 }
 
-type CacheableFunction = Extract<
-  keyof typescript.ModuleResolutionHost,
-  'fileExists' | 'directoryExists' | 'realpath'
->;
-const cacheableFunctions: CacheableFunction[] = [
-  'fileExists',
-  'directoryExists',
-  'realpath'
-];
-
-function addCache(servicesHost: typescript.ModuleResolutionHost) {
+function addCache(
+  servicesHost: typescript.ModuleResolutionHost
+): {
+  moduleResolutionHost: typescript.ModuleResolutionHost;
+  clearCache: () => void;
+} {
   const clearCacheFunctions: Action[] = [];
-
-  cacheableFunctions.forEach((functionToCache: CacheableFunction) => {
-    const originalFunction = servicesHost[functionToCache];
-    if (originalFunction !== undefined) {
-      const cache = createCache<ReturnType<typeof originalFunction>>(
-        originalFunction
-      );
-      servicesHost[
-        functionToCache
-      ] = cache.getCached as typescript.ModuleResolutionHost[CacheableFunction];
-      clearCacheFunctions.push(cache.clear);
-    }
-  });
-
-  return () => clearCacheFunctions.forEach(clear => clear());
-}
-
-function createCache<TOut>(originalFunction: (arg: string) => TOut) {
-  const cache = new Map<string, TOut>();
   return {
-    clear: () => {
-      cache.clear();
+    moduleResolutionHost: {
+      ...servicesHost,
+      fileExists: createCache(servicesHost.fileExists),
+      directoryExists:
+        servicesHost.directoryExists &&
+        createCache(servicesHost.directoryExists),
+      realpath: servicesHost.realpath && createCache(servicesHost.realpath)
     },
-    getCached: (arg: string) => {
+    clearCache: () => clearCacheFunctions.forEach(clear => clear())
+  };
+
+  function createCache<TOut>(originalFunction: (arg: string) => TOut) {
+    const cache = new Map<string, TOut>();
+    clearCacheFunctions.push(() => cache.clear());
+    return function getCached(arg: string) {
       let res = cache.get(arg);
       if (res !== undefined) {
         return res;
@@ -695,6 +687,6 @@ function createCache<TOut>(originalFunction: (arg: string) => TOut) {
       res = originalFunction(arg);
       cache.set(arg, res);
       return res;
-    }
-  };
+    };
+  }
 }
diff --git a/yarn.lock b/yarn.lock
index d8c6ffc16..f81b5d42a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2942,15 +2942,7 @@ js-tokens@^4.0.0:
   resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-4.0.0.tgz#19203fb59991df98e3a287050d4647cdeaf32499"
   integrity sha512-RdJUflcE3cUzKiMqQgsCu06FPu9UdIJO0beYbPhHN4k6apgJtifcoCtT9bcxOpYBtpD2kCM6Sbzg4CausW/PKQ==
 
-js-yaml@3.13.1, js-yaml@^3.9.0:
-  version "3.13.1"
-  resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-3.13.1.tgz#aff151b30bfdfa8e49e05da22e7415e9dfa37847"
-  integrity sha512-YfbcO7jXDdyj0DGxYVSlSeQNHbD7XPWvrVWeVUujrQEoZzWJIRrCPoyk6kL6IAjAG2IolMK4T0hNUe0HOUs5Jw==
-  dependencies:
-    argparse "^1.0.7"
-    esprima "^4.0.0"
-
-js-yaml@^3.13.0:
+js-yaml@3.13.1, js-yaml@^3.13.0, js-yaml@^3.9.0:
   version "3.13.1"
   resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-3.13.1.tgz#aff151b30bfdfa8e49e05da22e7415e9dfa37847"
   integrity sha512-YfbcO7jXDdyj0DGxYVSlSeQNHbD7XPWvrVWeVUujrQEoZzWJIRrCPoyk6kL6IAjAG2IolMK4T0hNUe0HOUs5Jw==
@@ -5041,10 +5033,10 @@ typedarray@^0.0.6:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
 
-typescript@^3.1.1:
-  version "3.4.5"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.4.5.tgz#2d2618d10bb566572b8d7aad5180d84257d70a99"
-  integrity sha512-YycBxUb49UUhdNMU5aJ7z5Ej2XGmaIBL0x34vZ82fn3hGvD+bgrMrVDpatgz2f7YxUMJxMkbWxJZeAvDxVe7Vw==
+typescript@^3.5.2:
+  version "3.5.2"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.5.2.tgz#a09e1dc69bc9551cadf17dba10ee42cf55e5d56c"
+  integrity sha512-7KxJovlYhTX5RaRbUdkAXN1KUZ8PwWlTzQdHV6xNqvuFOs7+WBo10TQUqT19Q/Jz2hk5v9TQDIhyLhhJY4p5AA==
 
 uglify-es@^3.3.4:
   version "3.3.9"