diff --git a/apps/files/lib/Sharing/Source/NodeShareSourceType.php b/apps/files/lib/Sharing/Source/NodeShareSourceType.php
index ea1a435e0223f..5db7f8a42b8b8 100644
--- a/apps/files/lib/Sharing/Source/NodeShareSourceType.php
+++ b/apps/files/lib/Sharing/Source/NodeShareSourceType.php
@@ -27,6 +27,7 @@
 use OCP\Interaction\InteractionResource;
 use OCP\Interaction\Resources\NodeResource;
 use OCP\IURLGenerator;
+use OCP\IUser;
 use OCP\L10N\IFactory;
 
 /**
@@ -72,8 +73,8 @@ public function getSourceIcon(string $source): ShareIconURL {
 	}
 
 	#[\Override]
-	public function getSourceInteractionResource(string $userId, string $source): InteractionResource {
-		return new NodeResource((int)$source, $userId);
+	public function getSourceInteractionResource(IUser $user, string $source): InteractionResource {
+		return new NodeResource((int)$source, $user->getUID());
 	}
 
 	#[\Override]
diff --git a/lib/private/Sharing/SharingManager.php b/lib/private/Sharing/SharingManager.php
index 76593a8f4bc0b..b6c0d465a25c8 100644
--- a/lib/private/Sharing/SharingManager.php
+++ b/lib/private/Sharing/SharingManager.php
@@ -698,7 +698,7 @@ private function validateInteraction(ShareAccessContext $accessContext, Share $s
 		$action = new ShareAction(null, array_values(array_map(static fn (SharePermission $permission): string => $permission->class, $share->getEnabledPermissions())));
 
 		$usersToCheck = [];
-		if ($share->owner->instance === null && ($ownerUser = $this->userManager->get($share->owner->userId)) !== null) {
+		if ($share->owner->instance === null && ($ownerUser = $this->userManager->get($share->owner->userId)) instanceof IUser) {
 			$usersToCheck[] = $ownerUser;
 		}
 
@@ -733,7 +733,7 @@ private function validateInteraction(ShareAccessContext $accessContext, Share $s
 					continue;
 				}
 
-				$resources[] = $sourceType->getSourceInteractionResource($userToCheck->getUID(), $source->value);
+				$resources[] = $sourceType->getSourceInteractionResource($userToCheck, $source->value);
 			}
 
 			$event = new RestrictInteractionEvent($userToCheck->getUID(), $userToCheck, $resources, $action, $receivers);
diff --git a/lib/unstable/Sharing/Source/IShareSourceType.php b/lib/unstable/Sharing/Source/IShareSourceType.php
index 0cce43c89731d..0cf5569f60b6b 100644
--- a/lib/unstable/Sharing/Source/IShareSourceType.php
+++ b/lib/unstable/Sharing/Source/IShareSourceType.php
@@ -13,6 +13,7 @@
 use NCU\Sharing\Icon\ShareIconURL;
 use OCP\AppFramework\Attribute\Implementable;
 use OCP\Interaction\InteractionResource;
+use OCP\IUser;
 use OCP\L10N\IFactory;
 
 /**
@@ -52,9 +53,8 @@ public function getSourceDisplayName(string $source): ?string;
 	public function getSourceIcon(string $source): null|ShareIconSVG|ShareIconURL;
 
 	/**
-	 * @param non-empty-string $userId
 	 * @param non-empty-string $source
 	 * @experimental 35.0.0
 	 */
-	public function getSourceInteractionResource(string $userId, string $source): InteractionResource;
+	public function getSourceInteractionResource(IUser $user, string $source): InteractionResource;
 }
diff --git a/tests/lib/Sharing/TestShareSourceType1.php b/tests/lib/Sharing/TestShareSourceType1.php
index e61bd869db945..904f8e63bfd11 100644
--- a/tests/lib/Sharing/TestShareSourceType1.php
+++ b/tests/lib/Sharing/TestShareSourceType1.php
@@ -13,6 +13,7 @@
 use NCU\Sharing\Icon\ShareIconURL;
 use NCU\Sharing\Source\IShareSourceType;
 use OCP\Interaction\InteractionResource;
+use OCP\IUser;
 use OCP\L10N\IFactory;
 
 class TestShareSourceType1 implements IShareSourceType {
@@ -45,7 +46,7 @@ public function getSourceIcon(string $source): null|ShareIconSVG|ShareIconURL {
 	}
 
 	#[\Override]
-	public function getSourceInteractionResource(string $userId, string $source): InteractionResource {
+	public function getSourceInteractionResource(IUser $user, string $source): InteractionResource {
 		return new TestInteractionResource($source);
 	}
 }