diff --git a/postinstall.js b/postinstall.js
index 5e2cd1f..4bee859 100644
--- a/postinstall.js
+++ b/postinstall.js
@@ -7,78 +7,100 @@ var upgrader = require("./tsconfig-upgrader");
 
 var projectDir = hook.findProjectDir();
 if (projectDir) {
-	var tsconfigPath = path.join(projectDir, "tsconfig.json");
-    var hasModules30 = upgrader.hasModules30(projectDir);
-	if (fs.existsSync(tsconfigPath)) {
-		upgrader.migrateTsConfig(tsconfigPath, projectDir);
-	} else {
-		createTsconfig(tsconfigPath);
-	}
-
-	if (!hasModules30) {
-		createReferenceFile();
-	}
-
-	installTypescript({force: hasModules30});
+    const tsconfigPath = path.join(projectDir, "tsconfig.json");
+    if (fs.existsSync(tsconfigPath)) {
+        upgrader.migrateTsConfig(tsconfigPath, projectDir);
+    } else {
+        createTsconfig(tsconfigPath);
+    }
+
+    const hasModules30 = upgrader.hasModules30(projectDir);
+    if (!hasModules30) {
+        createReferenceFile();
+    }
+
+    installTypescript(hasModules30);
 }
 
 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.";
+    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.";
 
-	if (!fs.existsSync(referenceFilePath)) {
-		fs.appendFileSync(referenceFilePath, content);
-	}
+    if (!fs.existsSync(referenceFilePath)) {
+        fs.appendFileSync(referenceFilePath, content);
+    }
 }
 
 function createTsconfig(tsconfigPath) {
-	var tsconfig = {};
+    var tsconfig = {};
 
-	tsconfig.compilerOptions = {
-		module: "commonjs",
-		target: "es5",
-		experimentalDecorators: true,
-		emitDecoratorMetadata: true,
-		noEmitHelpers: true,
-		noEmitOnError: true,
-	};
-	upgrader.migrateProject(tsconfig, tsconfigPath, projectDir);
+    tsconfig.compilerOptions = {
+        module: "commonjs",
+        target: "es5",
+        experimentalDecorators: true,
+        emitDecoratorMetadata: true,
+        noEmitHelpers: true,
+        noEmitOnError: true,
+    };
+    upgrader.migrateProject(tsconfig, tsconfigPath, projectDir);
 
-	tsconfig.exclude = ["node_modules", "platforms", "**/*.aot.ts"];
+    tsconfig.exclude = ["node_modules", "platforms", "**/*.aot.ts"];
 
-	fs.writeFileSync(tsconfigPath, JSON.stringify(tsconfig, null, 4));
+    fs.writeFileSync(tsconfigPath, JSON.stringify(tsconfig, null, 4));
 }
 
 function getProjectTypeScriptVersion() {
-	try {
-		var packageJsonPath = path.join(projectDir, "package.json"),
-			packageJsonContent = fs.readFileSync(packageJsonPath, "utf8"),
-			jsonContent = JSON.parse(packageJsonContent);
+    try {
+        var packageJsonPath = path.join(projectDir, "package.json"),
+            packageJsonContent = fs.readFileSync(packageJsonPath, "utf8"),
+            jsonContent = JSON.parse(packageJsonContent);
 
-		return (jsonContent.dependencies && jsonContent.dependencies.typescript) ||
+        return (jsonContent.dependencies && jsonContent.dependencies.typescript) ||
             (jsonContent.devDependencies && jsonContent.devDependencies.typescript);
-	} catch (err) {
-		console.error(err);
-		return null;
-	}
+    } catch (err) {
+        console.error(err);
+        return null;
+    }
 }
 
-function installTypescript({force = false} = {}) {
-	const installedTypeScriptVersion = getProjectTypeScriptVersion();
+function installTypescript(hasModules30) {
+    const installedTypeScriptVersion = getProjectTypeScriptVersion();
+    const force = shouldInstallLatest(installedTypeScriptVersion, hasModules30);
 
-	if (installedTypeScriptVersion && !force) {
-		console.log("Project already targets TypeScript " + installedTypeScriptVersion);
-	} else {
-        const command = force ? "npm install -D typescript@latest" : "npm update -D typescript";
+    if (installedTypeScriptVersion && !force) {
+        console.log(`Project already targets TypeScript ${installedTypeScriptVersion}`);
+    } else {
+        const command = force ?
+            "npm install -D typescript@latest" :
+            "npm install -D -E typescript@2.1.6"; // install exactly 2.1.6
 
         console.log("Installing TypeScript...");
 
-		require("child_process").exec(command, { cwd: projectDir }, function (err, stdout, stderr) {
-			if (err) {
-				console.warn("npm: " + err.toString());
-			}
-			process.stdout.write(stdout);
-			process.stderr.write(stderr);
-		});
-	}
+        require("child_process").exec(command, { cwd: projectDir }, (err, stdout, stderr) => {
+            if (err) {
+                console.warn(`npm: ${err.toString()}`);
+            }
+
+            process.stdout.write(stdout);
+            process.stderr.write(stderr);
+        });
+    }
+}
+
+function shouldInstallLatest(tsVersion, hasModules30) {
+    if (!hasModules30) {
+        return false;
+    }
+
+    const justVersion = clearPatch(tsVersion);
+    return !tsVersion ||
+        tsVersion === "2.2.0" ||
+        justVersion[0] < 2 || // ex. 1.8.10
+        justVersion[2] < 2; // ex. 2.1.6
+}
+
+function clearPatch(version) {
+    return version && (version.startsWith("~") || version.startsWith("^")) ?
+        version.substring(1) :
+        version;
 }