diff --git a/src/gui/macOS/fileproviderstorageuseenumerationobserver.h b/src/gui/macOS/fileproviderstorageuseenumerationobserver.h
index 285b159c3ae7b..897c865c9b235 100644
--- a/src/gui/macOS/fileproviderstorageuseenumerationobserver.h
+++ b/src/gui/macOS/fileproviderstorageuseenumerationobserver.h
@@ -21,5 +21,6 @@ typedef void(^UsageEnumerationFinishedHandler)(NSError *const error);
 
 @property (readwrite, strong) UsageEnumerationFinishedHandler enumerationFinishedHandler;
 @property (readonly) NSUInteger usage;
+@property (readonly) NSSet<id<NSFileProviderItem>> *materialisedItems;
 
 @end
diff --git a/src/gui/macOS/fileproviderstorageuseenumerationobserver.m b/src/gui/macOS/fileproviderstorageuseenumerationobserver.m
index c88fa8228e379..7ffc1a0b2bc6d 100644
--- a/src/gui/macOS/fileproviderstorageuseenumerationobserver.m
+++ b/src/gui/macOS/fileproviderstorageuseenumerationobserver.m
@@ -29,12 +29,17 @@ - (instancetype)init
 // NSFileProviderEnumerationObserver protocol methods
 - (void)didEnumerateItems:(NSArray<id<NSFileProviderItem>> *)updatedItems
 {
+    NSMutableSet<id<NSFileProviderItem>> * const existingItems = self.materialisedItems.mutableCopy;
+
     for (const id<NSFileProviderItem> item in updatedItems) {
         NSLog(@"StorageUseEnumerationObserver: Enumerating %@ with size %llu",
               item.filename, item.documentSize.unsignedLongLongValue);
 
         _usage += item.documentSize.unsignedLongLongValue;
+        [existingItems addObject:item];
     }
+
+    _materialisedItems = existingItems.copy;
 }
 
 - (void)finishEnumeratingWithError:(NSError *)error