diff --git a/lib/core.ts b/lib/core.ts
index c1d51a2..562ac4b 100644
--- a/lib/core.ts
+++ b/lib/core.ts
@@ -74,8 +74,6 @@ interface MathObject {
 //@ts-ignore
 declare const arguments: IArguments;
 declare const Math: MathObject;
-const NaN = 0 / 0;
-const Infinity = 1 / 0;
 
 declare var setTimeout: <T extends any[]>(handle: (...args: [ ...T, ...any[] ]) => void, delay?: number, ...args: T) => number;
 declare var setInterval: <T extends any[]>(handle: (...args: [ ...T, ...any[] ]) => void, delay?: number, ...args: T) => number;
diff --git a/lib/values/number.ts b/lib/values/number.ts
index 5a21c13..6b1dda6 100644
--- a/lib/values/number.ts
+++ b/lib/values/number.ts
@@ -12,8 +12,10 @@ interface NumberConstructor {
 }
 
 declare var Number: NumberConstructor;
-declare const parseInt: typeof Number.parseInt;
-declare const parseFloat: typeof Number.parseFloat;
+declare var parseInt: typeof Number.parseInt;
+declare var parseFloat: typeof Number.parseFloat;
+declare var NaN: number;
+declare var Infinity: number;
 
 gt.Number = function(this: Number | undefined, arg: any) {
     var val;
@@ -42,5 +44,7 @@ setProps(Number, {
     parseFloat(val) { return internals.parseFloat(val); },
 });
 
-(gt as any).parseInt = Number.parseInt;
-(gt as any).parseFloat = Number.parseFloat;
\ No newline at end of file
+Object.defineProperty(gt, 'parseInt', { value: Number.parseInt, writable: false });
+Object.defineProperty(gt, 'parseFloat', { value: Number.parseFloat, writable: false });
+Object.defineProperty(gt, 'NaN', { value: 0 / 0, writable: false });
+Object.defineProperty(gt, 'Infinity', { value: 1 / 0, writable: false });
diff --git a/src/me/topchetoeu/jscript/Main.java b/src/me/topchetoeu/jscript/Main.java
index aa92604..34a2426 100644
--- a/src/me/topchetoeu/jscript/Main.java
+++ b/src/me/topchetoeu/jscript/Main.java
@@ -54,7 +54,7 @@ public class Main {
 
     public static void main(String args[]) {
         var in = new BufferedReader(new InputStreamReader(System.in));
-        engine = new PolyfillEngine(new File("."));
+        engine = new TypescriptEngine(new File("."));
         var scope = engine.global().globalChild();
         var exited = new boolean[1];