diff --git src/plugins/platforms/cocoa/qcocoamenu.mm src/plugins/platforms/cocoa/qcocoamenu.mm
index 981d900..77eca5a 100644
--- src/plugins/platforms/cocoa/qcocoamenu.mm
+++ src/plugins/platforms/cocoa/qcocoamenu.mm
@@ -331,7 +331,7 @@ void QCocoaMenu::insertMenuItem(QPlatformMenuItem *menuItem, QPlatformMenuItem *
 
     // Empty menus on a menubar are hidden by default. If the menu gets
     // added to the menubar before it contains any item, we need to sync.
-    if (isVisible() && attachedItem().hidden) {
+    if (isVisible() && [m_attachedItem isHidden]) {
         if (auto *mb = qobject_cast<QCocoaMenuBar *>(menuParent()))
             mb->syncMenu(this);
     }
diff --git src/plugins/platforms/cocoa/qcocoanativeinterface.mm src/plugins/platforms/cocoa/qcocoanativeinterface.mm
index ee762f6..de47af3 100644
--- src/plugins/platforms/cocoa/qcocoanativeinterface.mm
+++ src/plugins/platforms/cocoa/qcocoanativeinterface.mm
@@ -172,12 +172,28 @@ void *QCocoaNativeInterface::NSPrintInfoForPrintEngine(QPrintEngine *printEngine
 
 QPixmap QCocoaNativeInterface::defaultBackgroundPixmapForQWizard()
 {
+    QCFType<CFURLRef> url109;
+    CFURLRef url = nullptr;
     const int ExpectedImageWidth = 242;
     const int ExpectedImageHeight = 414;
-    QCFType<CFArrayRef> urls = LSCopyApplicationURLsForBundleIdentifier(
-        CFSTR("com.apple.KeyboardSetupAssistant"), nullptr);
-    if (urls && CFArrayGetCount(urls) > 0) {
-        CFURLRef url = (CFURLRef)CFArrayGetValueAtIndex(urls, 0);
+    bool ok = false;
+    if (QSysInfo::macVersion() < QSysInfo::MV_10_10) {
+        if (LSFindApplicationForInfo(kLSUnknownCreator, CFSTR("com.apple.KeyboardSetupAssistant"),
+                                     0, 0, &url109) == noErr) {
+            url = url109;
+            ok = true;
+        }
+    } else {
+#if QT_OSX_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_10)
+        QCFType<CFArrayRef> urls = LSCopyApplicationURLsForBundleIdentifier(
+            CFSTR("com.apple.KeyboardSetupAssistant"), nullptr);
+        if (urls && CFArrayGetCount(urls) > 0) {
+            url = (CFURLRef)CFArrayGetValueAtIndex(urls, 0);
+            ok = true;
+        }
+#endif
+    }
+    if (ok) {
         QCFType<CFBundleRef> bundle = CFBundleCreate(kCFAllocatorDefault, url);
         if (bundle) {
             url = CFBundleCopyResourceURL(bundle, CFSTR("Background"), CFSTR("png"), 0);
diff --git src/plugins/platforms/cocoa/qcocoawindow.mm src/plugins/platforms/cocoa/qcocoawindow.mm
index 7f94e31..7516826 100644
--- src/plugins/platforms/cocoa/qcocoawindow.mm
+++ src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -60,6 +60,16 @@
 
 #include <vector>
 
+#if QT_MACOS_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_10)
+#   define NSWINPROPERTY(w,property,selector) (w).property
+#else
+#   define NSWINPROPERTY(w,property,selector) [(w) selector]
+#endif
+
+#ifndef __has_builtin
+#   define __has_builtin(x) false
+#endif
+
 enum {
     defaultWindowWidth = 160,
     defaultWindowHeight = 160
@@ -320,7 +326,14 @@ static void qt_closePopups()
 + (void)applicationActivationChanged:(NSNotification*)notification
 {
     const id sender = self;
+#if QT_MACOS_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_11)
+    // ObjC generics were introduced with Xcode 7 (= OS X 10.10) but only allow the compiler
+    // to generate errors when storing a deviant type. The 10.10SDK on 10.9 doesn't yet
+    // know about them, so we only support them from 10.11 onwards.
     NSEnumerator<NSWindow*> *windowEnumerator = nullptr;
+#else
+    NSEnumerator *windowEnumerator = nullptr;
+#endif
     NSApplication *application = [NSApplication sharedApplication];
 
 #if QT_MACOS_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_12)
@@ -779,7 +792,7 @@ void QCocoaWindow::show(bool becauseOfAncestor)
     if ([m_nsWindow isVisible])
         return;
 
-    if (m_view.window.parentWindow && !m_view.window.parentWindow.visible) {
+    if (m_view.window.parentWindow && !NSWINPROPERTY(m_view.window.parentWindow,visible,isVisible)) {
         m_hiddenByAncestor = true; // Parent still hidden, don't show now
     } else if ((becauseOfAncestor == m_hiddenByAncestor) // Was NEITHER explicitly hidden
                && !m_hiddenByClipping) { // ... NOR clipped
@@ -2095,11 +2108,11 @@ Qt::WindowState QCocoaWindow::windowState() const
     // FIXME: Support compound states (Qt::WindowStates)
 
     NSWindow *window = m_view.window;
-    if (window.miniaturized)
+    if (NSWINPROPERTY(window, miniaturized, isMiniaturized))
         return Qt::WindowMinimized;
     if (window.qt_fullScreen)
         return Qt::WindowFullScreen;
-    if ((window.zoomed && !isTransitioningToFullScreen())
+    if ((NSWINPROPERTY(window, zoomed, isZoomed) && !isTransitioningToFullScreen())
         || (m_lastReportedWindowState == Qt::WindowMaximized && isTransitioningToFullScreen()))
         return Qt::WindowMaximized;
 
@@ -2229,10 +2242,22 @@ void QCocoaWindow::applyContentBorderThickness(NSWindow *window)
 
     QMacAutoReleasePool pool;
 
+#if !__has_builtin(__builtin_available)  // #if __MAC_OS_X_VERSION_MAX_ALLOWED < 101200
+    bool hasTitlebarAppearsTransparent = [window respondsToSelector:@selector(setTitlebarAppearsTransparent:)];
+#endif
+
     if (!m_drawContentBorderGradient) {
         [window setStyleMask:[window styleMask] & ~NSTexturedBackgroundWindowMask];
         [[[window contentView] superview] setNeedsDisplay:YES];
-        window.titlebarAppearsTransparent = NO;
+#if __has_builtin(__builtin_available)  // #if __MAC_OS_X_VERSION_MAX_ALLOWED >= 101200
+        if (__builtin_available(macOS 10.10, *)) {
+            window.titlebarAppearsTransparent = NO;
+        }
+#else
+        if (hasTitlebarAppearsTransparent) {
+            [window setTitlebarAppearsTransparent:NO];
+        }
+#endif
         return;
     }
 
@@ -2257,7 +2282,15 @@ void QCocoaWindow::applyContentBorderThickness(NSWindow *window)
     int effectiveBottomContentBorderThickness = m_bottomContentBorderThickness;
 
     [window setStyleMask:[window styleMask] | NSTexturedBackgroundWindowMask];
-    window.titlebarAppearsTransparent = YES;
+#if __has_builtin(__builtin_available)  // #if __MAC_OS_X_VERSION_MAX_ALLOWED >= 101200
+    if (__builtin_available(macOS 10.10, *)) {
+        window.titlebarAppearsTransparent = YES;
+    }
+#else
+    if (hasTitlebarAppearsTransparent) {
+        [window setTitlebarAppearsTransparent:YES];
+    }
+#endif
 
     [window setContentBorderThickness:effectiveTopContentBorderThickness forEdge:NSMaxYEdge];
     [window setAutorecalculatesContentBorderThickness:NO forEdge:NSMaxYEdge];