diff --git a/src/platform_impl/ios/mod.rs b/src/platform_impl/ios/mod.rs
index 06ce41ace..ebd962b31 100644
--- a/src/platform_impl/ios/mod.rs
+++ b/src/platform_impl/ios/mod.rs
@@ -65,7 +65,8 @@
 // window size/position.
 macro_rules! assert_main_thread {
     ($($t:tt)*) => {
-        if !msg_send![class!(NSThread), isMainThread] {
+        let is_main_thread: ::objc::runtime::BOOL = msg_send!(class!(NSThread), isMainThread);
+        if is_main_thread == ::objc::runtime::NO {
             panic!($($t)*);
         }
     };
diff --git a/src/platform_impl/ios/window.rs b/src/platform_impl/ios/window.rs
index f0fee5dc5..8fd8f28ba 100644
--- a/src/platform_impl/ios/window.rs
+++ b/src/platform_impl/ios/window.rs
@@ -229,7 +229,7 @@ impl Inner {
       let uiscreen = match monitor {
         Some(Fullscreen::Exclusive(video_mode)) => {
           let uiscreen = video_mode.video_mode.monitor.ui_screen() as id;
-          let () = msg_send![uiscreen, setCurrentMode: video_mode.video_mode.screen_mode];
+          let () = msg_send![uiscreen, setCurrentMode: video_mode.video_mode.screen_mode.0];
           uiscreen
         }
         Some(Fullscreen::Borderless(monitor)) => monitor
diff --git a/src/platform_impl/macos/app_state.rs b/src/platform_impl/macos/app_state.rs
index 4fcc01f4b..bf8f0bc9e 100644
--- a/src/platform_impl/macos/app_state.rs
+++ b/src/platform_impl/macos/app_state.rs
@@ -20,9 +20,7 @@ use cocoa::{
   base::{id, nil},
   foundation::{NSAutoreleasePool, NSSize},
 };
-use objc::runtime::YES;
-
-use objc::runtime::Object;
+use objc::runtime::{Object, BOOL, NO, YES};
 
 use crate::{
   dpi::LogicalSize,
@@ -347,14 +345,16 @@ impl AppState {
   }
 
   pub fn queue_event(wrapper: EventWrapper) {
-    if !unsafe { msg_send![class!(NSThread), isMainThread] } {
+    let is_main_thread: BOOL = unsafe { msg_send!(class!(NSThread), isMainThread) };
+    if is_main_thread == NO {
       panic!("Event queued from different thread: {:#?}", wrapper);
     }
     HANDLER.events().push_back(wrapper);
   }
 
   pub fn queue_events(mut wrappers: VecDeque<EventWrapper>) {
-    if !unsafe { msg_send![class!(NSThread), isMainThread] } {
+    let is_main_thread: BOOL = unsafe { msg_send!(class!(NSThread), isMainThread) };
+    if is_main_thread == NO {
       panic!("Events queued from different thread: {:#?}", wrappers);
     }
     HANDLER.events().append(&mut wrappers);
@@ -388,8 +388,9 @@ impl AppState {
 
         let dialog_open = if window_count > 1 {
           let dialog: id = msg_send![windows, lastObject];
-          let is_main_window: bool = msg_send![dialog, isMainWindow];
-          msg_send![dialog, isVisible] && !is_main_window
+          let is_main_window: BOOL = msg_send![dialog, isMainWindow];
+          let is_visible: BOOL = msg_send![dialog, isVisible];
+          is_visible != NO && is_main_window == NO
         } else {
           false
         };
@@ -404,9 +405,9 @@ impl AppState {
         pool.drain();
 
         if window_count > 0 {
-          let window: id = msg_send![windows, objectAtIndex:0];
-          let window_has_focus = msg_send![window, isKeyWindow];
-          if !dialog_open && window_has_focus && dialog_is_closing {
+          let window: id = msg_send![windows, firstObject];
+          let window_has_focus: BOOL = msg_send![window, isKeyWindow];
+          if !dialog_open && window_has_focus != NO && dialog_is_closing {
             HANDLER.dialog_is_closing.store(false, Ordering::SeqCst);
           }
           if dialog_open {
diff --git a/src/platform_impl/macos/event_loop.rs b/src/platform_impl/macos/event_loop.rs
index 7ff8faa70..353dedc1b 100644
--- a/src/platform_impl/macos/event_loop.rs
+++ b/src/platform_impl/macos/event_loop.rs
@@ -14,9 +14,9 @@ use std::{
 };
 
 use cocoa::{
-  appkit::{NSApp, NSEventType::NSApplicationDefined},
-  base::{id, nil, YES},
-  foundation::{NSAutoreleasePool, NSPoint},
+  appkit::{NSApp, NSEventModifierFlags, NSEventSubtype, NSEventType::NSApplicationDefined},
+  base::{id, nil, BOOL, NO, YES},
+  foundation::{NSAutoreleasePool, NSInteger, NSPoint, NSTimeInterval},
 };
 use crossbeam_channel::{self as channel, Receiver, Sender};
 use scopeguard::defer;
@@ -107,7 +107,8 @@ pub struct EventLoop<T: 'static> {
 impl<T> EventLoop<T> {
   pub fn new() -> Self {
     let delegate = unsafe {
-      if !msg_send![class!(NSThread), isMainThread] {
+      let is_main_thread: BOOL = msg_send!(class!(NSThread), isMainThread);
+      if is_main_thread == NO {
         panic!("On macOS, `EventLoop` must be created on the main thread!");
       }
 
@@ -200,13 +201,13 @@ pub unsafe fn post_dummy_event(target: id) {
       event_class,
       otherEventWithType: NSApplicationDefined
       location: NSPoint::new(0.0, 0.0)
-      modifierFlags: 0
-      timestamp: 0
-      windowNumber: 0
+      modifierFlags: NSEventModifierFlags::empty()
+      timestamp: 0 as NSTimeInterval
+      windowNumber: 0 as NSInteger
       context: nil
-      subtype: 0
-      data1: 0
-      data2: 0
+      subtype: NSEventSubtype::NSWindowExposedEventType
+      data1: 0 as NSInteger
+      data2: 0 as NSInteger
   ];
   let () = msg_send![target, postEvent: dummy_event atStart: YES];
 }
diff --git a/src/platform_impl/macos/ffi.rs b/src/platform_impl/macos/ffi.rs
index 26958aafa..f3cd43328 100644
--- a/src/platform_impl/macos/ffi.rs
+++ b/src/platform_impl/macos/ffi.rs
@@ -112,6 +112,7 @@ pub const kCGCursorWindowLevelKey: NSInteger = 19;
 pub const kCGNumberOfWindowLevelKeys: NSInteger = 20;
 
 #[derive(Debug, Clone, Copy)]
+#[repr(isize)]
 pub enum NSWindowLevel {
   NSNormalWindowLevel = kCGBaseWindowLevelKey as _,
   NSFloatingWindowLevel = kCGFloatingWindowLevelKey as _,
diff --git a/src/platform_impl/macos/util/async.rs b/src/platform_impl/macos/util/async.rs
index d6e2b3165..00521e13c 100644
--- a/src/platform_impl/macos/util/async.rs
+++ b/src/platform_impl/macos/util/async.rs
@@ -15,7 +15,7 @@ use dispatch::Queue;
 use menu::Menu;
 use objc::{
   rc::autoreleasepool,
-  runtime::{NO, YES},
+  runtime::{BOOL, NO, YES},
 };
 
 use crate::{
@@ -57,7 +57,8 @@ pub unsafe fn set_style_mask_async(ns_window: id, ns_view: id, mask: NSWindowSty
   });
 }
 pub unsafe fn set_style_mask_sync(ns_window: id, ns_view: id, mask: NSWindowStyleMask) {
-  if msg_send![class!(NSThread), isMainThread] {
+  let is_main_thread: BOOL = msg_send!(class!(NSThread), isMainThread);
+  if is_main_thread != NO {
     set_style_mask(ns_window, ns_view, mask);
   } else {
     let ns_window = MainThreadSafe(ns_window);
diff --git a/src/platform_impl/macos/util/mod.rs b/src/platform_impl/macos/util/mod.rs
index ee904f6e6..05b758109 100644
--- a/src/platform_impl/macos/util/mod.rs
+++ b/src/platform_impl/macos/util/mod.rs
@@ -48,7 +48,7 @@ impl IdRef {
   #[allow(dead_code)]
   pub fn retain(inner: id) -> IdRef {
     if inner != nil {
-      let () = unsafe { msg_send![inner, retain] };
+      let _: id = unsafe { msg_send![inner, retain] };
     }
     IdRef(inner)
   }
@@ -84,10 +84,7 @@ impl Deref for IdRef {
 
 impl Clone for IdRef {
   fn clone(&self) -> IdRef {
-    if self.0 != nil {
-      let _: id = unsafe { msg_send![self.0, retain] };
-    }
-    IdRef(self.0)
+    IdRef::retain(self.0)
   }
 }
 
@@ -147,8 +144,8 @@ pub unsafe fn app_name() -> Option<id> {
 }
 
 pub unsafe fn superclass<'a>(this: &'a Object) -> &'a Class {
-  let superclass: id = msg_send![this, superclass];
-  &*(superclass as *const _)
+  let superclass: *const Class = msg_send![this, superclass];
+  &*superclass
 }
 
 pub unsafe fn create_input_context(view: id) -> IdRef {
diff --git a/src/platform_impl/macos/view.rs b/src/platform_impl/macos/view.rs
index 92d946141..764260aad 100644
--- a/src/platform_impl/macos/view.rs
+++ b/src/platform_impl/macos/view.rs
@@ -5,7 +5,7 @@ use std::{
   boxed::Box,
   collections::{HashSet, VecDeque},
   os::raw::*,
-  slice, str,
+  ptr, slice, str,
   sync::{Arc, Mutex, Weak},
 };
 
@@ -349,7 +349,7 @@ extern "C" fn view_did_move_to_window(this: &Object, _sel: Sel) {
     let tracking_rect: NSInteger = msg_send![this,
         addTrackingRect:rect
         owner:this
-        userData:nil
+        userData:ptr::null_mut::<c_void>()
         assumeInside:NO
     ];
     state.tracking_rect = Some(tracking_rect);
@@ -370,7 +370,7 @@ extern "C" fn frame_did_change(this: &Object, _sel: Sel, _event: id) {
     let tracking_rect: NSInteger = msg_send![this,
         addTrackingRect:rect
         owner:this
-        userData:nil
+        userData:ptr::null_mut::<c_void>()
         assumeInside:NO
     ];
 
@@ -462,8 +462,8 @@ extern "C" fn set_marked_text(
   trace!("Triggered `setMarkedText`");
   unsafe {
     let marked_text_ref = clear_marked_text(this);
-    let has_attr = msg_send![string, isKindOfClass: class!(NSAttributedString)];
-    if has_attr {
+    let has_attr: BOOL = msg_send![string, isKindOfClass: class!(NSAttributedString)];
+    if has_attr != NO {
       marked_text_ref.initWithAttributedString(string);
     } else {
       marked_text_ref.initWithString(string);
@@ -538,8 +538,8 @@ extern "C" fn insert_text(this: &Object, _sel: Sel, string: id, _replacement_ran
     let state_ptr: *mut c_void = *this.get_ivar("taoState");
     let state = &mut *(state_ptr as *mut ViewState);
 
-    let has_attr = msg_send![string, isKindOfClass: class!(NSAttributedString)];
-    let characters = if has_attr {
+    let has_attr: BOOL = msg_send![string, isKindOfClass: class!(NSAttributedString)];
+    let characters = if has_attr != NO {
       // This is a *mut NSAttributedString
       msg_send![string, string]
     } else {
@@ -1006,7 +1006,7 @@ fn mouse_motion(this: &Object, event: id) {
       || view_point.x > view_rect.size.width
       || view_point.y > view_rect.size.height
     {
-      let mouse_buttons_down: NSInteger = msg_send![class!(NSEvent), pressedMouseButtons];
+      let mouse_buttons_down: NSUInteger = msg_send![class!(NSEvent), pressedMouseButtons];
       if mouse_buttons_down == 0 {
         // Point is outside of the client area (view) and no buttons are pressed
         return;
diff --git a/src/platform_impl/macos/window.rs b/src/platform_impl/macos/window.rs
index c38bc4847..c5f18fdf2 100644
--- a/src/platform_impl/macos/window.rs
+++ b/src/platform_impl/macos/window.rs
@@ -4,6 +4,7 @@
 use raw_window_handle::{AppKitHandle, RawWindowHandle};
 use std::{
   collections::VecDeque,
+  convert::TryInto,
   f64,
   os::raw::c_void,
   sync::{
@@ -38,7 +39,7 @@ use cocoa::{
     NSWindowStyleMask,
   },
   base::{id, nil},
-  foundation::{NSAutoreleasePool, NSDictionary, NSPoint, NSRect, NSSize},
+  foundation::{NSAutoreleasePool, NSDictionary, NSPoint, NSRect, NSSize, NSUInteger},
 };
 use core_graphics::display::{CGDisplay, CGDisplayMode};
 use objc::{
@@ -347,7 +348,8 @@ impl UnownedWindow {
     pl_attribs: PlatformSpecificWindowBuilderAttributes,
   ) -> Result<(Arc<Self>, IdRef), RootOsError> {
     unsafe {
-      if !msg_send![class!(NSThread), isMainThread] {
+      let is_main_thread: BOOL = msg_send!(class!(NSThread), isMainThread);
+      if is_main_thread == NO {
         panic!("Windows can only be created on the main thread on macOS");
       }
     }
@@ -1089,9 +1091,9 @@ impl UnownedWindow {
       let desc = NSScreen::deviceDescription(screen);
       let key = util::ns_string_id_ref("NSScreenNumber");
       let value = NSDictionary::valueForKey_(desc, *key);
-      let display_id = msg_send![value, unsignedIntegerValue];
+      let display_id: NSUInteger = msg_send![value, unsignedIntegerValue];
       RootMonitorHandle {
-        inner: MonitorHandle::new(display_id),
+        inner: MonitorHandle::new(display_id.try_into().unwrap()),
       }
     }
   }