diff --git a/library/modules/platform/uikit.sx b/library/modules/platform/uikit.sx
index 22180b7..c712a1f 100644
--- a/library/modules/platform/uikit.sx
+++ b/library/modules/platform/uikit.sx
@@ -217,12 +217,12 @@ SxSceneDelegate :: #objc_class("SxSceneDelegate") {
         uikit_scene_will_connect(xx self, xx 0, scene, session, options);
     }
 
-    window :: (self: *Self) -> *void {
-        if g_uikit_plat == null { return xx 0; }
+    window :: (self: *Self) -> ?*UIWindow {
+        if g_uikit_plat == null { return null; }
         return g_uikit_plat.window;
     }
 
-    setWindow :: (self: *Self, w: *void) {
+    setWindow :: (self: *Self, w: ?*UIWindow) {
         if g_uikit_plat == null { return; }
         g_uikit_plat.window = w;
     }
@@ -247,12 +247,15 @@ GpuMode :: enum {
 }
 
 UIKitPlatform :: struct {
-    window: *void = null;   // UIWindow*
-    root_vc: *void = null;  // UIViewController*
-    gl_view: *void = null;  // SxGLView* OR SxMetalView* (depending on gpu_mode)
-    gl_layer: *void = null; // CAEAGLLayer* OR CAMetalLayer* (= gl_view.layer)
-    gl_ctx: *void = null;   // EAGLContext* (null in metal mode)
-    display_link: *void = null;
+    window: ?*UIWindow = null;
+    root_vc: ?*UIViewController = null;
+    // SxGLView (gles mode) or SxMetalView (metal mode) — both extend
+    // UIView, so the common method surface is reachable as *UIView.
+    gl_view: ?*UIView = null;
+    // CAEAGLLayer (gles) or CAMetalLayer (metal) — both extend CALayer.
+    gl_layer: ?*CALayer = null;
+    gl_ctx: ?*EAGLContext = null;
+    display_link: ?*CADisplayLink = null;
     color_renderbuffer: u32 = 0;
     framebuffer: u32 = 0;
     gl_initialized: bool = false;
diff --git a/src/ir/lower.zig b/src/ir/lower.zig
index 7ce9072..d0a2a22 100644
--- a/src/ir/lower.zig
+++ b/src/ir/lower.zig
@@ -4713,6 +4713,14 @@ pub const Lowering = struct {
                     try out.appendSlice(self.alloc, "^v");
                 }
             },
+            .optional => |o| {
+                // sx's `?T` is a nullable T. At the Obj-C ABI boundary
+                // nullability is just "this pointer may be null" — the
+                // wire-level encoding is the same as T. Unwrap and
+                // recurse. (Same goes for `?*UIView` etc. — the
+                // underlying pointer kind drives the encoding char.)
+                return self.appendObjcEncoding(out, o.child, span);
+            },
             else => return self.bailObjcEncoding(span, "type kind not yet supported by Obj-C encoding", @intFromEnum(std.meta.activeTag(info))),
         }
     }