diff --git a/Sources/PlaydateKit/Graphics/Classes/TileMap.swift b/Sources/PlaydateKit/Graphics/Classes/TileMap.swift
index daa1003..cc7e72d 100644
--- a/Sources/PlaydateKit/Graphics/Classes/TileMap.swift
+++ b/Sources/PlaydateKit/Graphics/Classes/TileMap.swift
@@ -48,14 +48,22 @@ extension Graphics {
 
         /// Fills the tilemap with `indexes`, `rowWidth` tiles per row. The
         /// tilemap is resized to fit.
-        public func setTiles(_ indexes: [UInt16], rowWidth: Int) {
-            var indexes = indexes
-            indexes.withUnsafeMutableBufferPointer { buffer in
-                tilemapAPI.pointee.setTiles.unsafelyUnwrapped(pointer, buffer.baseAddress,
-                                                      Int32(buffer.count), Int32(rowWidth))
+        public func setTiles(_ indexes: Span<UInt16>, rowWidth: Int) {
+            indexes.withUnsafeBufferPointer { buffer in
+                // The C API takes a non-const pointer but only reads the
+                // indexes, copying them into the tilemap.
+                tilemapAPI.pointee.setTiles.unsafelyUnwrapped(
+                    pointer, UnsafeMutablePointer(mutating: buffer.baseAddress),
+                    Int32(buffer.count), Int32(rowWidth))
             }
         }
 
+        /// Fills the tilemap with `indexes`, `rowWidth` tiles per row. The
+        /// tilemap is resized to fit.
+        public func setTiles(_ indexes: [UInt16], rowWidth: Int) {
+            indexes.withUnsafeBufferPointer { setTiles($0.span, rowWidth: rowWidth) }
+        }
+
         /// Sets the tile index at position (x, y).
         public func setTile(x: Int, y: Int, index: UInt16) {
             tilemapAPI.pointee.setTileAtPosition.unsafelyUnwrapped(pointer, Int32(x), Int32(y), index)
diff --git a/Tests/PlaydateKit/MockPlaydate.swift b/Tests/PlaydateKit/MockPlaydate.swift
index 972bdae..f6b16e2 100644
--- a/Tests/PlaydateKit/MockPlaydate.swift
+++ b/Tests/PlaydateKit/MockPlaydate.swift
@@ -24,6 +24,7 @@ enum Mock {
     nonisolated(unsafe) static let soundEffectAPI = UnsafeMutablePointer<playdate_sound_effect>.allocate(capacity: 1)
     nonisolated(unsafe) static let lfoAPI = UnsafeMutablePointer<playdate_sound_lfo>.allocate(capacity: 1)
     nonisolated(unsafe) static let delayLineAPI = UnsafeMutablePointer<playdate_sound_effect_delayline>.allocate(capacity: 1)
+    nonisolated(unsafe) static let tilemapAPI = UnsafeMutablePointer<playdate_tilemap>.allocate(capacity: 1)
     nonisolated(unsafe) static let fileAPI = UnsafeMutablePointer<playdate_file>.allocate(capacity: 1)
     nonisolated(unsafe) static let jsonAPI = UnsafeMutablePointer<playdate_json>.allocate(capacity: 1)
     nonisolated(unsafe) static let apiStruct = UnsafeMutablePointer<PlaydateAPI>.allocate(capacity: 1)
@@ -38,6 +39,9 @@ enum Mock {
     /// Caps the bytes a file read returns (0 = end of file, negative =
     /// error); `nil` fills the whole request.
     nonisolated(unsafe) static var fileReadLimit: Int32?
+    /// The index buffer and count last handed to `setTiles`.
+    nonisolated(unsafe) static var tilesPointer: UnsafeMutablePointer<UInt16>?
+    nonisolated(unsafe) static var tilesCount: Int32 = 0
     /// Userdata stored per sprite / menu item, as the OS would keep it.
     nonisolated(unsafe) static var spriteUserdata: [OpaquePointer: UnsafeMutableRawPointer] = [:]
     nonisolated(unsafe) static var menuUserdata: [OpaquePointer: UnsafeMutableRawPointer] = [:]
@@ -87,6 +91,8 @@ enum Mock {
         buttonState = (0, 0, 0)
         patternBytes = []
         fileReadLimit = nil
+        tilesPointer = nil
+        tilesCount = 0
         spriteUserdata = [:]
         menuUserdata = [:]
         menuCallback = nil
@@ -174,6 +180,19 @@ enum Mock {
 
     private static func installGraphics() {
         gfxAPI.initialize(to: playdate_graphics())
+        tilemapAPI.initialize(to: playdate_tilemap())
+        gfxAPI.pointee.tilemap = UnsafePointer(tilemapAPI)
+
+        tilemapAPI.pointee.newTilemap = {
+            Mock.record("newTilemap")
+            return Mock.fakePointer()
+        }
+        tilemapAPI.pointee.freeTilemap = { _ in Mock.record("freeTilemap") }
+        tilemapAPI.pointee.setTiles = { _, indexes, count, rowWidth in
+            Mock.record("setTiles(\(count),\(rowWidth))")
+            Mock.tilesPointer = indexes
+            Mock.tilesCount = count
+        }
 
         gfxAPI.pointee.fillRect = { x, y, width, height, color in
             if color > 3, let pattern = UnsafeRawPointer(bitPattern: color) {
diff --git a/Tests/PlaydateKit/WrapperTests.swift b/Tests/PlaydateKit/WrapperTests.swift
index f5b7434..6a19984 100644
--- a/Tests/PlaydateKit/WrapperTests.swift
+++ b/Tests/PlaydateKit/WrapperTests.swift
@@ -99,6 +99,16 @@ struct WrapperTests {
         #expect(visited == 1)
     }
 
+    @Test func tileMapSetTilesPassesTheCallersStorageWithoutCopying() {
+        let tileMap = Graphics.TileMap()
+        let indexes: [UInt16] = [1, 2, 3, 4, 5, 6]
+        tileMap.setTiles(indexes, rowWidth: 3)
+
+        #expect(Mock.events.contains("setTiles(6,3)"))
+        let storage = indexes.withUnsafeBufferPointer { $0.baseAddress }
+        #expect(UnsafePointer(Mock.tilesPointer) == storage)
+    }
+
     // MARK: Sprite
 
     @Test func spriteUserdataRecoversWrapperInCallbacks() {