diff --git a/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs b/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs
index fc06a46f..6c5200ed 100644
--- a/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs
+++ b/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs
@@ -105,7 +105,8 @@ public class ActivityHandlerService(
 		activity.Object = await objectResolver.ResolveObject(activity.Object, actor.Uri) as ASNote ??
 		                  throw GracefulException.UnprocessableEntity("Failed to resolve create object");
 
-		await noteSvc.ProcessNoteAsync(activity.Object, actor, inboxUser);
+		using (await NoteService.GetNoteProcessLockAsync(activity.Object.Id))
+			await noteSvc.ProcessNoteAsync(activity.Object, actor, inboxUser);
 	}
 
 	private async Task HandleDelete(ASDelete activity, User resolvedActor)
@@ -335,7 +336,8 @@ public class ActivityHandlerService(
 				await userSvc.UpdateUserAsync(resolvedActor, actor);
 				break;
 			case ASNote note:
-				await noteSvc.ProcessNoteUpdateAsync(note, resolvedActor);
+				using (await NoteService.GetNoteProcessLockAsync(note.Id))
+					await noteSvc.ProcessNoteUpdateAsync(note, resolvedActor);
 				break;
 			default:
 				logger.LogDebug("Like activity object is unknown, skipping");
diff --git a/Iceshrimp.Backend/Core/Services/NoteService.cs b/Iceshrimp.Backend/Core/Services/NoteService.cs
index 36f1c5f4..9c3ea1a0 100644
--- a/Iceshrimp.Backend/Core/Services/NoteService.cs
+++ b/Iceshrimp.Backend/Core/Services/NoteService.cs
@@ -715,6 +715,8 @@ public class NoteService(
 			eventSvc.RaiseNoteDeleted(this, hit);
 	}
 
+	public static ValueTask<IDisposable> GetNoteProcessLockAsync(string uri) => KeyedLocker.LockAsync(uri);
+
 	public async Task<Note?> ProcessNoteAsync(ASNote note, User actor, User? user = null)
 	{
 		var dbHit = await db.Notes.IncludeCommonProperties().FirstOrDefaultAsync(p => p.Uri == note.Id);