diff --git a/App/Composition/SmiliePicker/SmilieSearchViewModel.swift b/App/Composition/SmiliePicker/SmilieSearchViewModel.swift
index 26da62eda..70a48901c 100644
--- a/App/Composition/SmiliePicker/SmilieSearchViewModel.swift
+++ b/App/Composition/SmiliePicker/SmilieSearchViewModel.swift
@@ -197,12 +197,24 @@ final class SmilieSearchViewModel: ObservableObject {
     
     func updateLastUsedDate(for smilie: Smilie) {
         guard let context = dataStore.managedObjectContext else { return }
-        context.perform {
-            smilie.metadata.lastUsedDate = Date()
-            do {
-                try context.save()
-            } catch {
-                print("Error saving last used date: \(error)")
+        let smilieID = smilie.objectID
+        Task {
+            await context.perform {
+                guard let smilie = context.object(with: smilieID) as? Smilie,
+                      let smilieText = smilie.text else { return }
+
+                let fetchRequest = NSFetchRequest<Smilie>(entityName: "Smilie")
+                fetchRequest.predicate = NSPredicate(format: "text == %@", smilieText)
+                fetchRequest.fetchLimit = 1
+
+                do {
+                    if let smilie = try context.fetch(fetchRequest).first {
+                        smilie.metadata.lastUsedDate = Date()
+                        try context.save()
+                    }
+                } catch {
+                    print("Error saving last used date: \(error)")
+                }
             }
         }
     }
diff --git a/App/Refreshers/AnnouncementListRefresher.swift b/App/Refreshers/AnnouncementListRefresher.swift
index 7eeeccded..c567e247a 100644
--- a/App/Refreshers/AnnouncementListRefresher.swift
+++ b/App/Refreshers/AnnouncementListRefresher.swift
@@ -3,7 +3,7 @@
 //  Copyright 2017 Awful Contributors. CC BY-NC-SA 3.0 US https://github.com/Awful/Awful.app
 
 import AwfulCore
-import CoreData
+@preconcurrency import CoreData
 import os
 import UIKit
 
diff --git a/App/View Controllers/Posts/PostsPageViewController.swift b/App/View Controllers/Posts/PostsPageViewController.swift
index 77720bd45..31e12e867 100644
--- a/App/View Controllers/Posts/PostsPageViewController.swift	
+++ b/App/View Controllers/Posts/PostsPageViewController.swift	
@@ -2,12 +2,12 @@
 //
 //  Copyright 2016 Awful Contributors. CC BY-NC-SA 3.0 US https://github.com/Awful/Awful.app
 
-import AwfulCore
+@preconcurrency import AwfulCore
 import AwfulModelTypes
 import AwfulSettings
 import AwfulTheming
 import Combine
-import CoreData
+@preconcurrency import CoreData
 import MobileCoreServices
 import MRProgress
 import os
@@ -41,7 +41,9 @@ final class PostsPageViewController: ViewController {
     @FoilDefaultStorage(Settings.jumpToPostEndOnDoubleTap) private var jumpToPostEndOnDoubleTap
     private var jumpToPostIDAfterLoading: String?
     private var messageViewController: MessageComposeViewController?
-    private var networkOperation: Task<(posts: [Post], firstUnreadPost: Int?, advertisementHTML: String), Error>?
+    // Stored as Any because Task returns non-Sendable Core Data objects (Post: NSManagedObject).
+    // Swift 6 requires Task<Success, Failure> Success types to be Sendable.
+    private var networkOperation: Any?
     private var observers: [NSKeyValueObservation] = []
     private lazy var oEmbedFetcher: OEmbedFetcher = .init()
     private(set) var page: ThreadPage?
@@ -160,7 +162,7 @@ final class PostsPageViewController: ViewController {
     }
 
     deinit {
-        networkOperation?.cancel()
+        (networkOperation as? Task<(posts: [Post], firstUnreadPost: Int?, advertisementHTML: String), Error>)?.cancel()
     }
 
     var posts: [Post] = []
@@ -198,7 +200,7 @@ final class PostsPageViewController: ViewController {
     ) {
         flagRequest?.cancel()
         flagRequest = nil
-        networkOperation?.cancel()
+        (networkOperation as? Task<(posts: [Post], firstUnreadPost: Int?, advertisementHTML: String), Error>)?.cancel()
         networkOperation = nil
 
         // prevent white flash caused by webview being opaque during refreshes
diff --git a/AwfulCore/Sources/AwfulCore/Model/AwfulManagedObject.swift b/AwfulCore/Sources/AwfulCore/Model/AwfulManagedObject.swift
index 447acb7f6..0ee7c99a0 100644
--- a/AwfulCore/Sources/AwfulCore/Model/AwfulManagedObject.swift
+++ b/AwfulCore/Sources/AwfulCore/Model/AwfulManagedObject.swift
@@ -5,7 +5,7 @@
 import CoreData
 
 /// A slightly more convenient NSManagedObject for entities with a custom class.
-public class AwfulManagedObject: NSManagedObject {
+public class AwfulManagedObject: NSManagedObject, @unchecked Sendable {
     public var objectKey: AwfulObjectKey {
         fatalError("subclass implementation please")
     }
diff --git a/AwfulCore/Sources/AwfulCore/Model/Post.swift b/AwfulCore/Sources/AwfulCore/Model/Post.swift
index da37f0d28..1bfaecb36 100644
--- a/AwfulCore/Sources/AwfulCore/Model/Post.swift
+++ b/AwfulCore/Sources/AwfulCore/Model/Post.swift
@@ -6,7 +6,7 @@ import CoreData
 
 /// A single reply to a thread.
 @objc(Post)
-public class Post: AwfulManagedObject, Managed {
+public class Post: AwfulManagedObject, Managed, @unchecked Sendable {
     public static var entityName: String { "Post" }
     
     /// Whether the logged-in user can edit the post.
diff --git a/Config/Common.xcconfig b/Config/Common.xcconfig
index 3aefd43a2..ede9fae37 100644
--- a/Config/Common.xcconfig
+++ b/Config/Common.xcconfig
@@ -75,6 +75,7 @@ RUN_CLANG_STATIC_ANALYZER = YES
 SDKROOT = iphoneos
 
 SWIFT_EMIT_LOC_STRINGS = YES
+SWIFT_STRICT_CONCURRENCY = minimal
 SWIFT_TREAT_WARNINGS_AS_ERRORS = YES
 SWIFT_VERSION = 5.0