diff --git a/Frameworks/Find/src/FindWindowController.mm b/Frameworks/Find/src/FindWindowController.mm
index 258e5b20..6bd3c9e1 100644
--- a/Frameworks/Find/src/FindWindowController.mm
+++ b/Frameworks/Find/src/FindWindowController.mm
@@ -312,12 +312,18 @@ static NSButton* OakCreateStopSearchButton ()
 
 - (void)applicationDidActivate:(NSNotification*)notification
 {
-	self.window.collectionBehavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
+	// Starting with 10.11 behavior must be changed after current event loop cycle <rdar://23587833>
+	dispatch_async(dispatch_get_main_queue(), ^{
+		self.window.collectionBehavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
+	});
 }
 
 - (void)applicationDidDeactivate:(NSNotification*)notification
 {
-	self.window.collectionBehavior &= ~NSWindowCollectionBehaviorMoveToActiveSpace;
+	// Starting with 10.11 behavior must be changed after current event loop cycle <rdar://23587833>
+	dispatch_async(dispatch_get_main_queue(), ^{
+		self.window.collectionBehavior &= ~NSWindowCollectionBehaviorMoveToActiveSpace;
+	});
 }
 
 - (void)menuNeedsUpdate:(NSMenu*)aMenu
diff --git a/Frameworks/HTMLOutputWindow/src/HTMLOutputWindow.mm b/Frameworks/HTMLOutputWindow/src/HTMLOutputWindow.mm
index dc02bc00..d21f8a17 100644
--- a/Frameworks/HTMLOutputWindow/src/HTMLOutputWindow.mm
+++ b/Frameworks/HTMLOutputWindow/src/HTMLOutputWindow.mm
@@ -43,12 +43,18 @@ OAK_DEBUG_VAR(HTMLOutputWindow);
 
 - (void)applicationDidActivate:(NSNotification*)notification
 {
-	self.window.collectionBehavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
+	// Starting with 10.11 behavior must be changed after current event loop cycle <rdar://23587833>
+	dispatch_async(dispatch_get_main_queue(), ^{
+		self.window.collectionBehavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
+	});
 }
 
 - (void)applicationDidDeactivate:(NSNotification*)notification
 {
-	self.window.collectionBehavior &= ~NSWindowCollectionBehaviorMoveToActiveSpace;
+	// Starting with 10.11 behavior must be changed after current event loop cycle <rdar://23587833>
+	dispatch_async(dispatch_get_main_queue(), ^{
+		self.window.collectionBehavior &= ~NSWindowCollectionBehaviorMoveToActiveSpace;
+	});
 }
 
 + (HTMLOutputWindowController*)HTMLOutputWindowWithRunner:(command::runner_ptr const&)aRunner