diff --git a/public/assets/portal.png b/public/assets/portal.png
index 240a9a1..9197be3 100644
Binary files a/public/assets/portal.png and b/public/assets/portal.png differ
diff --git a/src/engine/config/sprites.ts b/src/engine/config/sprites.ts
index 0a4f9b5..3614488 100644
--- a/src/engine/config/sprites.ts
+++ b/src/engine/config/sprites.ts
@@ -110,10 +110,10 @@ const bubbleSpriteSpec = {
 SPRITE_SPECS.set(Sprites.BUBBLE, bubbleSpriteSpec);
 
 const portalSpriteSpec = {
-  msPerFrame: 200,
+  msPerFrame: 150,
   width: 64,
   height: 64,
-  frames: 3,
+  frames: 9,
   sheet: "/assets/portal.png",
 };
 SPRITE_SPECS.set(Sprites.PORTAL, portalSpriteSpec);
diff --git a/src/engine/entities/LambdaFactory.ts b/src/engine/entities/LambdaFactory.ts
index 9ad1398..770c096 100644
--- a/src/engine/entities/LambdaFactory.ts
+++ b/src/engine/entities/LambdaFactory.ts
@@ -143,12 +143,19 @@ export class LambdaFactory extends Entity {
   }
 
   private spawnNewLambda(direction: Direction) {
+    try {
+      parse(this.code);
+    } catch (e: any) {
+      SOUNDS.get(Failure.name)!.play();
+      return;
+    }
+
     const spawner = this.getComponent<GridSpawn>(ComponentNames.GridSpawn);
     spawner.spawnEntity(direction);
 
-    const text = this.getComponent<Text>(ComponentNames.Text);
-    text.text = spawner.spawnsLeft.toString();
-    this.addComponent(text);
+    const textComponent = this.getComponent<Text>(ComponentNames.Text);
+    textComponent.text = spawner.spawnsLeft.toString();
+    this.addComponent(textComponent);
 
     SOUNDS.get(LambdaTransformSound.name)!.play();
   }
diff --git a/src/engine/levels/Tutorial.ts b/src/engine/levels/Tutorial.ts
index 165b10f..694c8ff 100644
--- a/src/engine/levels/Tutorial.ts
+++ b/src/engine/levels/Tutorial.ts
@@ -22,8 +22,7 @@ export class Tutorial extends Level {
       new Wall({ x: 11, y: 10 }),
       new Curry({ x: 10, y: 10 }),
       new LockedDoor({ x: 9, y: 10 }),
-      new LambdaFactory({ x: 6, y: 3 }, "(λ (x) . x)", 3),
-
+      new LambdaFactory({ x: 6, y: 3 }, "// TODO: Remove line\n(λ (x) . x)", 3),
       new FunctionApplication({ x: 6, y: 6 }, "(_INPUT key)"),
     ];
 
diff --git a/src/interpreter/PeggyParser.js b/src/interpreter/PeggyParser.js
index 632f1b7..5671d91 100644
--- a/src/interpreter/PeggyParser.js
+++ b/src/interpreter/PeggyParser.js
@@ -201,7 +201,7 @@ export default (function () {
     );
   };
 
-  function peg$parse(input, options, allowUnderscores = false) {
+  function peg$parse(input, options) {
     options = options !== undefined ? options : {};
 
     var peg$FAILED = {};
@@ -215,7 +215,7 @@ export default (function () {
     var peg$c2 = ".";
     var peg$c3 = "\r\n";
 
-    var peg$r0 = allowUnderscores ? /^[a-zA-Z0-9]_/ : /^[a-zA-Z0-9]/;
+    var peg$r0 = /^[a-zA-Z0-9]/;
     var peg$r1 = /^[\\\u03BB]/;
     var peg$r2 = /^[\t-\n ]/;
 
diff --git a/src/interpreter/parser.ts b/src/interpreter/parser.ts
index d288815..5e3be0f 100644
--- a/src/interpreter/parser.ts
+++ b/src/interpreter/parser.ts
@@ -30,10 +30,6 @@ export const isVariable = (term: LambdaTerm): term is Variable => {
   return typeof term === "string";
 };
 
-export const parse = (
-  term: string,
-  allowUnderscores = false,
-  library = false,
-) => {
-  return peggyParser.parse(term, { peg$library: library }, allowUnderscores);
+export const parse = (term: string, library = false) => {
+  return peggyParser.parse(term, { peg$library: library });
 };