diff --git a/src/main.rs b/src/main.rs
index c11d41e..0c6e249 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -31,11 +31,7 @@ fn check_map(r: &robot::Robot, w: &world::World) -> Result<(), String> {
 }
 
 /// Check if the robot collide with another one at the given position.
-fn check_collisions(
-    r: &robot::Robot,
-    w: &world::World,
-    h: &HashMap<&robot::Position, &u32>,
-) -> Result<(), String> {
+fn check_collisions(r: &robot::Robot, h: &HashMap<robot::Position, u32>) -> Result<(), String> {
     match h.get(&r.p) {
         Some(&x) => Err(format!(
             "The robot id: {} collided with robot id: {} in position: ({};{}) !",
@@ -262,10 +258,9 @@ mod tests {
             robot::Position { x: 2, y: 3 },
             vec!['F'],
         );
-        let w = world::World { x: 10, y: 10 };
 
-        let mut h: HashMap<&robot::Position, &u32> = HashMap::new();
-        h.insert(&robot::Position { x: 2, y: 3 }, &1);
-        assert!(check_collisions(&r, &w, &h).is_ok());
+        let mut h: HashMap<robot::Position, u32> = HashMap::new();
+        h.insert(robot::Position { x: 2, y: 3 }, 1);
+        assert!(check_collisions(&r, &h).is_ok());
     }
 }