diff --git a/src/DifBuilder.hx b/src/DifBuilder.hx
index 92b8283b..87c5f89f 100644
--- a/src/DifBuilder.hx
+++ b/src/DifBuilder.hx
@@ -103,6 +103,8 @@ class DifBuilder {
 			for (j in hull.surfaceStart...(hull.surfaceStart + hull.surfaceCount)) {
 				var surfaceindex = geo.hullSurfaceIndices[j];
 				var surface = geo.surfaces[surfaceindex];
+				if (surface == null)
+					continue;
 				var planeindex = surface.planeIndex;
 
 				var planeFlipped = (planeindex & 0x8000) == 0x8000;
diff --git a/src/Main.hx b/src/Main.hx
index b8176e12..4aaf9ac3 100644
--- a/src/Main.hx
+++ b/src/Main.hx
@@ -52,7 +52,7 @@ class Main extends hxd.App {
 	override function init() {
 		super.init();
 
-		var ltr = File.getContent("data/missions/beginner/movement.mis");
+		var ltr = File.getContent("data/missions/advanced/acrobat.mis");
 		var mfp = new MisParser(ltr);
 		var mis = mfp.parse();
 
diff --git a/src/Marble.hx b/src/Marble.hx
index bae3f39d..27242adb 100644
--- a/src/Marble.hx
+++ b/src/Marble.hx
@@ -691,8 +691,8 @@ class Marble extends GameObject {
 			if (timeRemaining <= 0)
 				break;
 
-			var timeStep = 0.00800000037997961;
-			if (timeRemaining < 0.00800000037997961)
+			var timeStep = 0.002;
+			if (timeRemaining < 0.002)
 				timeStep = timeRemaining;
 
 			var tempState = timeState.clone();
@@ -774,9 +774,15 @@ class Marble extends GameObject {
 				this.heldPowerup = null;
 			}
 
+			if (this.controllable) {
+				var tempTimeState = timeState.clone();
+				tempState.currentAttemptTime = piTime;
+				tempState.dt = timeStep;
+				this.level.callCollisionHandlers(cast this, tempTimeState);
+			}
+
 			timeRemaining -= timeStep;
-			it++;
-		} while (it <= 10);
+		} while (true);
 		this.queuedContacts = [];
 	}
 
diff --git a/src/MarbleWorld.hx b/src/MarbleWorld.hx
index 5ac00bea..a6628ac2 100644
--- a/src/MarbleWorld.hx
+++ b/src/MarbleWorld.hx
@@ -593,9 +593,6 @@ class MarbleWorld extends Scheduler {
 		this.particleManager.update(1000 * timeState.timeSinceLoad, dt);
 		this.playGui.update(timeState);
 
-		if (this.marble != null) {
-			callCollisionHandlers(marble);
-		}
 		this.updateTexts();
 	}
 
@@ -677,7 +674,7 @@ class MarbleWorld extends Scheduler {
 		this.playGui.formatGemCounter(this.gemCount, this.totalGems);
 	}
 
-	function callCollisionHandlers(marble:Marble) {
+	public function callCollisionHandlers(marble:Marble, timeState:TimeState) {
 		var contacts = this.collisionWorld.radiusSearch(marble.getAbsPos().getPosition(), marble._radius);
 		var newImmunity = [];
 		var calledShapes = [];