diff --git a/src/exit.rs b/src/exit.rs
index c523f1a..7571989 100644
--- a/src/exit.rs
+++ b/src/exit.rs
@@ -1,4 +1,4 @@
-use crate::{from_base36, Position, ToBase36};
+use crate::Position;
 use std::str::FromStr;
 use std::error::Error;
 use std::fmt;
diff --git a/src/game.rs b/src/game.rs
index 8376d5c..7f714e3 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -1,5 +1,4 @@
-use crate::{Dialogue, Ending, Font, Item, Palette, Room, Sprite, TextDirection, Tile, ToBase36, Variable, transform_line_endings, segments_from_string, to_base36, from_base36};
-use std::error::Error;
+use crate::{Dialogue, Ending, Font, Item, Palette, Room, Sprite, TextDirection, Tile, Variable, transform_line_endings, segments_from_string, from_base36, new_unique_id};
 use loe::TransformMode;
 use std::str::FromStr;
 
@@ -359,23 +358,9 @@ impl Game {
     /// first available tile ID.
     /// e.g. if current tile IDs are [0, 2, 3] the result will be `1`
     ///      if current tile IDs are [0, 1, 2] the result will be `3`
-    /// todo this needs to be a generic function that takes a vec of string IDs and returns a new base64 string ID
     #[inline]
     pub fn new_tile_id(&self) -> String {
-        let mut new_id = 0;
-
-        let mut ids = self.tile_ids();
-        ids.sort();
-
-        for id in ids {
-            if new_id == from_base36(id.as_ref()) {
-                new_id += 1;
-            } else {
-                return to_base36(new_id);
-            }
-        }
-
-        to_base36(new_id + 1)
+        new_unique_id(self.tile_ids())
     }
 
     /// adds a tile safely and returns the new tile ID
diff --git a/src/room.rs b/src/room.rs
index 0f4733c..973bf16 100644
--- a/src/room.rs
+++ b/src/room.rs
@@ -1,4 +1,4 @@
-use crate::{from_base36, optional_data_line, Exit, ExitInstance, Instance, Position, ToBase36};
+use crate::{optional_data_line, Exit, ExitInstance, Instance, Position};
 use crate::game::{RoomType, RoomFormat};
 use crate::exit::Transition;
 use std::str::FromStr;
diff --git a/src/sprite.rs b/src/sprite.rs
index 18b3186..20a82af 100644
--- a/src/sprite.rs
+++ b/src/sprite.rs
@@ -1,4 +1,4 @@
-use crate::{from_base36, optional_data_line, AnimationFrames, Image, Position, ToBase36};
+use crate::{optional_data_line, AnimationFrames, Image, Position};
 use crate::image::animation_frames_from_string;
 use std::str::FromStr;
 
diff --git a/src/tile.rs b/src/tile.rs
index 09b747a..5a1a5aa 100644
--- a/src/tile.rs
+++ b/src/tile.rs
@@ -1,4 +1,4 @@
-use crate::{from_base36, optional_data_line, AnimationFrames, Image, ToBase36};
+use crate::{optional_data_line, AnimationFrames, Image};
 use crate::image::animation_frames_from_string;
 
 #[derive(Clone, Debug, Eq, PartialEq)]