diff --git a/bin/ns-upgrade-tsconfig b/bin/ns-upgrade-tsconfig
new file mode 100644
index 0000000..e8e093e
--- /dev/null
+++ b/bin/ns-upgrade-tsconfig
@@ -0,0 +1,7 @@
+#!/usr/bin/env node
+var path = require("path");
+var upgrader = require("../tsconfig-upgrader");
+
+var projectDir = path.dirname(path.dirname(path.dirname(__dirname)));
+var tsConfigPath = path.join(projectDir, "tsconfig.json");
+upgrader.migrateTsConfig(tsConfigPath, projectDir);
diff --git a/bin/ns-upgrade-tsconfig.cmd b/bin/ns-upgrade-tsconfig.cmd
new file mode 100644
index 0000000..2f7a4c2
--- /dev/null
+++ b/bin/ns-upgrade-tsconfig.cmd
@@ -0,0 +1 @@
+@node %~dp0\ns-upgrade-tsconfig %*
diff --git a/package.json b/package.json
index 3c8deac..dd233c0 100644
--- a/package.json
+++ b/package.json
@@ -1,12 +1,15 @@
 {
   "name": "nativescript-dev-typescript",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "TypeScript support for NativeScript projects. Install using `tns install typescript`.",
   "scripts": {
     "test": "exit 0",
     "postinstall": "node postinstall.js",
     "preuninstall": "node preuninstall.js"
   },
+  "bin": {
+    "ns-upgrade-tsconfig": "./bin/ns-upgrade-tsconfig"
+  },
   "nativescript": {
     "hooks": [
       {
diff --git a/postinstall.js b/postinstall.js
index 1a95f6c..6f350e5 100644
--- a/postinstall.js
+++ b/postinstall.js
@@ -3,126 +3,31 @@ hook.postinstall();
 
 var fs = require("fs");
 var path = require("path");
-
-var __migrations = [
-	inlineSourceMapMigration,
-	addDomLibs,
-	addIterableToAngularProjects,
-];
-
+var upgrader = require("./tsconfig-upgrader");
 
 var projectDir = hook.findProjectDir();
 if (projectDir) {
 	var tsconfigPath = path.join(projectDir, "tsconfig.json");
 	if (fs.existsSync(tsconfigPath)) {
-		migrateTsconfig(tsconfigPath);
+		upgrader.migrateTsConfig(tsconfigPath, projectDir);
 	} else {
 		createTsconfig(tsconfigPath);
 	}
-	createReferenceFile();
+	if (!upgrader.hasModules30(projectDir)) {
+		createReferenceFile();
+	}
 	installTypescript();
 }
 
 function createReferenceFile() {
 	var referenceFilePath = path.join(projectDir, "references.d.ts"),
-		content = '/// <reference path="./node_modules/tns-core-modules/tns-core-modules.d.ts" /> Needed for autocompletion and compilation.';
+		content = "/// <reference path=\"./node_modules/tns-core-modules/tns-core-modules.d.ts\" /> Needed for autocompletion and compilation.";
 
 	if (!fs.existsSync(referenceFilePath)) {
 		fs.appendFileSync(referenceFilePath, content);
 	}
 }
 
-function inlineSourceMapMigration(existingConfig, displayableTsconfigPath) {
-	if (existingConfig.compilerOptions) {
-		if ("sourceMap" in existingConfig["compilerOptions"]) {
-			delete existingConfig["compilerOptions"]["sourceMap"];
-			console.warn("> Deleted \"compilerOptions.sourceMap\" setting in \"" + displayableTsconfigPath + "\".");
-			console.warn("> Inline source maps will be used when building in Debug configuration from now on.");
-		}
-	}
-}
-
-function addIterableToAngularProjects(existingConfig) {
-	var packageJsonPath = path.join(projectDir, "package.json");
-	var packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
-	var dependencies = packageJson.dependencies || [];
-
-	var hasAngular = Object.keys(dependencies).includes("nativescript-angular");
-    var hasRelevantAngularVersion = /[4-9]\.\d+\.\d+/i.test(dependencies["@angular/core"]);
-	if (hasAngular && hasRelevantAngularVersion) {
-        console.log("Adding 'es2015.iterable' lib to tsconfig.json...");
-		addTsLib(existingConfig, "es2015.iterable");
-	}
-}
-
-function addDomLibs(existingConfig) {
-	function relevantModulesVersion(version) {
-		return /[3-9]\.\d+\.\d+/i.test(version);
-	}
-
-	function hasRelevantModulesDependency() {
-		var packageJsonPath = path.join(projectDir, "package.json");
-		var packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
-		var dependencies = packageJson.dependencies || [];
-
-		return relevantModulesVersion(dependencies["tns-core-modules"]);
-	}
-
-	function hasRelevantModulesPackage() {
-		var packageJsonPath = path.join(projectDir, "node_modules", "tns-core-modules", "package.json");
-		if (!fs.existsSync(packageJsonPath)) {
-			return false;
-		}
-
-		var packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
-		return relevantModulesVersion(packageJson.version);
-	}
-
-	if (hasRelevantModulesDependency() || hasRelevantModulesPackage()) {
-        console.log("Adding 'es6' lib to tsconfig.json...");
-		addTsLib(existingConfig, "es6");
-        console.log("Adding 'dom' lib to tsconfig.json...");
-		addTsLib(existingConfig, "dom");
-	}
-}
-
-function addTsLib(existingConfig, libName) {
-	if (existingConfig.compilerOptions) {
-		var options = existingConfig.compilerOptions;
-		if (!options.lib) {
-			options.lib = [];
-		}
-		if (!options.lib.find(function(l) {
-				return libName.toLowerCase() === l.toLowerCase();
-			})) {
-			options.lib.push(libName);
-		}
-	}
-}
-
-function migrateTsconfig(tsconfigPath) {
-	var displayableTsconfigPath = path.relative(projectDir, tsconfigPath);
-
-	function withTsConfig(action) {
-		var existingConfig = null;
-		try {
-			var existingConfigContents = fs.readFileSync(tsconfigPath);
-			existingConfig = JSON.parse(existingConfigContents);
-		} catch (e) {
-			console.error("Invalid " + displayableTsconfigPath + ": " + e);
-			return;
-		}
-		action(existingConfig);
-		fs.writeFileSync(tsconfigPath, JSON.stringify(existingConfig, null, 4));
-	}
-
-	withTsConfig(function(existingConfig) {
-		__migrations.forEach(function(migration) {
-			migration(existingConfig, displayableTsconfigPath);
-		});
-	});
-}
-
 function createTsconfig(tsconfigPath) {
 	var tsconfig = {};
 
@@ -134,8 +39,7 @@ function createTsconfig(tsconfigPath) {
 		noEmitHelpers: true,
 		noEmitOnError: true,
 	};
-	addDomLibs(tsconfig);
-	addIterableToAngularProjects(tsconfig);
+	upgrader.migrateProject(tsconfig, tsconfigPath, projectDir);
 
 	tsconfig.exclude = ["node_modules", "platforms", "**/*.aot.ts"];
 
diff --git a/tsconfig-upgrader.js b/tsconfig-upgrader.js
new file mode 100644
index 0000000..fa5aba4
--- /dev/null
+++ b/tsconfig-upgrader.js
@@ -0,0 +1,126 @@
+var fs = require("fs");
+var path = require("path");
+
+var __migrations = [
+	inlineSourceMapMigration,
+	addDomLibs,
+	addIterableToAngularProjects,
+	addTnsCoreModulesPathMappings,
+];
+
+function migrateProject(tsConfig, tsconfigPath, projectDir) {
+	var displayableTsconfigPath = path.relative(projectDir, tsconfigPath);
+	__migrations.forEach(function(migration) {
+		migration(tsConfig, displayableTsconfigPath, projectDir);
+	});
+}
+exports.migrateProject = migrateProject;
+
+function migrateTsConfig(tsconfigPath, projectDir) {
+	var displayableTsconfigPath = path.relative(projectDir, tsconfigPath);
+
+	function withTsConfig(action) {
+		var existingConfig = null;
+		try {
+			var existingConfigContents = fs.readFileSync(tsconfigPath);
+			existingConfig = JSON.parse(existingConfigContents);
+		} catch (e) {
+			console.error("Invalid " + displayableTsconfigPath + ": " + e);
+			return;
+		}
+		action(existingConfig);
+		fs.writeFileSync(tsconfigPath, JSON.stringify(existingConfig, null, 4));
+	}
+
+	withTsConfig(function(existingConfig) {
+		migrateProject(existingConfig, displayableTsconfigPath, projectDir);
+	});
+}
+exports.migrateTsConfig = migrateTsConfig;
+
+function inlineSourceMapMigration(existingConfig, displayableTsconfigPath) {
+	if (existingConfig.compilerOptions) {
+		if ("sourceMap" in existingConfig["compilerOptions"]) {
+			delete existingConfig["compilerOptions"]["sourceMap"];
+			console.warn("> Deleted \"compilerOptions.sourceMap\" setting in \"" + displayableTsconfigPath + "\".");
+			console.warn("> Inline source maps will be used when building in Debug configuration from now on.");
+		}
+	}
+}
+
+function addIterableToAngularProjects(existingConfig, displayableTsconfigPath, projectDir) {
+	var packageJsonPath = path.join(projectDir, "package.json");
+	var packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
+	var dependencies = packageJson.dependencies || [];
+
+	var hasAngular = Object.keys(dependencies).includes("nativescript-angular");
+    var hasRelevantAngularVersion = /[4-9]\.\d+\.\d+/i.test(dependencies["@angular/core"]);
+	if (hasAngular && hasRelevantAngularVersion) {
+        console.log("Adding 'es2015.iterable' lib to tsconfig.json...");
+		addTsLib(existingConfig, "es2015.iterable");
+	}
+}
+
+function hasModules30(projectDir) {
+	function relevantModulesVersion(version) {
+		return /[3-9]\.\d+\.\d+/i.test(version);
+	}
+
+	function hasRelevantModulesDependency() {
+		var packageJsonPath = path.join(projectDir, "package.json");
+		var packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
+		var dependencies = packageJson.dependencies || [];
+
+		return relevantModulesVersion(dependencies["tns-core-modules"]);
+	}
+
+	function hasRelevantModulesPackage() {
+		var packageJsonPath = path.join(projectDir, "node_modules", "tns-core-modules", "package.json");
+		if (!fs.existsSync(packageJsonPath)) {
+			return false;
+		}
+
+		var packageJson = JSON.parse(fs.readFileSync(packageJsonPath));
+		return relevantModulesVersion(packageJson.version);
+	}
+
+	return hasRelevantModulesDependency() || hasRelevantModulesPackage();
+}
+exports.hasModules30 = hasModules30;
+
+function addDomLibs(existingConfig, displayableTsconfigPath, projectDir) {
+	if (hasModules30(projectDir)) {
+		console.log("Adding 'es6' lib to tsconfig.json...");
+		addTsLib(existingConfig, "es6");
+		console.log("Adding 'dom' lib to tsconfig.json...");
+		addTsLib(existingConfig, "dom");
+	}
+}
+
+function addTsLib(existingConfig, libName) {
+	if (existingConfig.compilerOptions) {
+		var options = existingConfig.compilerOptions;
+		if (!options.lib) {
+			options.lib = [];
+		}
+		if (!options.lib.find(function(l) {
+				return libName.toLowerCase() === l.toLowerCase();
+			})) {
+			options.lib.push(libName);
+		}
+	}
+}
+
+function addTnsCoreModulesPathMappings(existingConfig, displayableTsconfigPath, projectDir) {
+	if (hasModules30(projectDir)) {
+		console.log("Adding tns-core-modules path mappings lib to tsconfig.json...");
+		existingConfig["compilerOptions"] = existingConfig["compilerOptions"] || {};
+		var compilerOptions = existingConfig["compilerOptions"];
+		compilerOptions["baseUrl"] = ".";
+		compilerOptions["paths"] = compilerOptions["paths"] || {};
+		compilerOptions["paths"]["*"] = [
+			"./node_modules/tns-core-modules/*",
+			"./node_modules/*"
+		];
+	}
+}