diff --git a/lib/Service/UserMigrationService.php b/lib/Service/UserMigrationService.php
index 2cd988ec..184a7977 100644
--- a/lib/Service/UserMigrationService.php
+++ b/lib/Service/UserMigrationService.php
@@ -115,11 +115,19 @@ public function estimateExportSize(IUser $user, ?array $filteredMigratorList = n
 	public function checkExportability(IUser $user, ?array $filteredMigratorList = null): void {
 		try {
 			$userFolder = $this->rootFolder->getUserFolder($user->getUID());
-			$freeSpace = ceil($userFolder->getFreeSpace() / 1024);
+			$freeSpace = $userFolder->getFreeSpace();
+			if ($freeSpace > 0) {
+				$freeSpace = ceil($freeSpace / 1024);
+			}
 		} catch (Throwable $e) {
 			throw new NotExportableException('Error calculating amount of free storage space available');
 		}
 
+		if ($freeSpace < 0) {
+			// Free space is unknown or unlimited, no need to check for export size
+			return;
+		}
+
 		try {
 			$exportFile = $userFolder->get(ExportDestination::EXPORT_FILENAME);
 			if (!($exportFile instanceof File)) {