diff --git a/src/corelib/world.c b/src/corelib/world.c
index 85fbed4..8a063e9 100644
--- a/src/corelib/world.c
+++ b/src/corelib/world.c
@@ -166,7 +166,7 @@ void update_collision() {
 	}
 }
 
-object_t* interpolate_move(object_t* object, float target_x, float target_y, float max_step_size) {
+void interpolate_move(object_t* object, float target_x, float target_y, float max_step_size, int slide) {
 	// calculate step delta
 	float dx = target_x - object->sprite.x, dy = target_y - object->sprite.y;
 	// calculate direction x,y
@@ -179,7 +179,7 @@ object_t* interpolate_move(object_t* object, float target_x, float target_y, flo
 	if(!_can_collide(object)) {
 		object->sprite.x = target_x;
 		object->sprite.y = target_y;
-		return NULL;
+		return;
 	}
 
 	/*
@@ -208,11 +208,11 @@ object_t* interpolate_move(object_t* object, float target_x, float target_y, flo
 				object_broadcast_collision(object, other);
 				object->sprite.x = old_x;
 				object->sprite.y = old_y;
-				return other;
+				return;
 			}
 		}
 	}
 
 	// no collision, return nothing
-	return NULL;
+	return;
 }
diff --git a/src/corelib/world.h b/src/corelib/world.h
index 2c57f31..27de091 100644
--- a/src/corelib/world.h
+++ b/src/corelib/world.h
@@ -62,6 +62,6 @@ void draw_objects();
 
 void update_collision();
 
-object_t* interpolate_move(object_t* object, float target_x, float target_y, float max_step_size);
+void interpolate_move(object_t* object, float target_x, float target_y, float max_step_size, int slide);
 
 #endif /* _world_h */