diff --git a/assets/sound/vo/aperture_ai/03_part1_entry-1.sox b/assets/sound/vo/aperture_ai/03_part1_entry-1.sox
new file mode 100644
index 0000000..5ad82e6
--- /dev/null
+++ b/assets/sound/vo/aperture_ai/03_part1_entry-1.sox
@@ -0,0 +1 @@
+-c 1 -r 22050
diff --git a/assets/sound/vo/aperture_ai/03_part1_entry-2.sox b/assets/sound/vo/aperture_ai/03_part1_entry-2.sox
new file mode 100644
index 0000000..5ad82e6
--- /dev/null
+++ b/assets/sound/vo/aperture_ai/03_part1_entry-2.sox
@@ -0,0 +1 @@
+-c 1 -r 22050
diff --git a/src/physics/collision_object.c b/src/physics/collision_object.c
index 80d0f6e..cae8029 100644
--- a/src/physics/collision_object.c
+++ b/src/physics/collision_object.c
@@ -149,6 +149,11 @@ void collisionObjectCollideWithQuadSwept(struct CollisionObject* object, struct
         return;
     }
 
+    // quads with a thickness of 0 are one sided
+    if (quad->thickness == 0.0f && vector3Dot(&result.normal, &quad->plane.normal) < 0.0f) {
+        return;
+    }
+
     int touchingPortals = collisionSceneIsTouchingPortal(&result.contactA, &result.normal);
 
     if (touchingPortals) {