diff --git a/shard.lock b/shard.lock
new file mode 100644
index 0000000..8f5dc10
--- /dev/null
+++ b/shard.lock
@@ -0,0 +1,6 @@
+version: 2.0
+shards:
+  sdl:
+    git: https://github.com/ysbaddaden/sdl.cr.git
+    version: 0.1.0+git.commit.d7b2a9b754660ca7f4a03dd3dbe6f3d9395da7d6
+
diff --git a/src/naka/map.cr b/src/naka/map.cr
index 42209af..44e1c5c 100644
--- a/src/naka/map.cr
+++ b/src/naka/map.cr
@@ -102,7 +102,9 @@ class Naka::Map
 	end
 
 	def get(x, y)
-		get_chunk(x / CHUNK_SIZE, y / CHUNK_SIZE).get(x % CHUNK_SIZE, y % CHUNK_SIZE)
+		x_value = x / CHUNK_SIZE
+		y_value = y / CHUNK_SIZE
+		get_chunk(x_value.to_i, y_value.to_i).get(x % CHUNK_SIZE, y % CHUNK_SIZE)
 	end
 end
 
diff --git a/src/naka/naka.cr b/src/naka/naka.cr
index e795f8d..48105a6 100644
--- a/src/naka/naka.cr
+++ b/src/naka/naka.cr
@@ -88,14 +88,14 @@ class Naka::Timer
 	getter last_update
 
 	def initialize
-		@start = Time.now
+		@start = Time.local
 		@last_update = @start
 	end
 
 	def step
-		now = Time.now
+		now = Time.local
 
-		dt = now.epoch_ms - @last_update.epoch_ms
+		dt = now.to_unix_ms - @last_update.to_unix_ms
 
 		@last_update = now