diff --git a/spec/controllers/admin/backups_controller_spec.rb b/spec/controllers/admin/backups_controller_spec.rb
index 4551558e5..092a945bc 100644
--- a/spec/controllers/admin/backups_controller_spec.rb
+++ b/spec/controllers/admin/backups_controller_spec.rb
@@ -198,7 +198,8 @@ describe Admin::BackupsController do
       describe "when filename contains invalid characters" do
         it "should raise an error" do
           ['灰色.tar.gz', '; echo \'haha\'.tar.gz'].each do |invalid_filename|
-            xhr :post, :upload_backup_chunk, resumableFilename: invalid_filename, resumableTotalSize: '0'
+            described_class.any_instance.expects(:has_enough_space_on_disk?).returns(true)
+            xhr :post, :upload_backup_chunk, resumableFilename: invalid_filename, resumableTotalSize: 1
 
             expect(response.status).to eq(415)
             expect(response.body).to eq(I18n.t('backup.invalid_filename'))
@@ -208,9 +209,11 @@ describe Admin::BackupsController do
 
       describe "when filename is valid" do
         it "should upload the file successfully" do
+          described_class.any_instance.expects(:has_enough_space_on_disk?).returns(true)
+
           xhr :post, :upload_backup_chunk,
             resumableFilename: 'test.tar.gz',
-            resumableTotalSize: '0',
+            resumableTotalSize: 1,
             resumableIdentifier: 'test',
             resumableChunkNumber: '1',
             resumableChunkSize: '1',