diff --git a/ci-build.cmd b/ci-build.cmd
index f658252c9f..ae0dd9b713 100644
--- a/ci-build.cmd
+++ b/ci-build.cmd
@@ -20,7 +20,7 @@ CALL git clone --branch=%APPVEYOR_REPO_BRANCH% %REPO_URL% %DIST_SRC_DIR%
 cd %DIST_SRC_DIR%
 CALL git checkout %APPVEYOR_REPO_COMMIT%
 CALL git submodule update --init --recursive
-DEL /S %DIST_SRC_DIR%.git\objects\pack\*
+DEL /S/Q %DIST_SRC_DIR%.git\objects\pack\*
 cd %DIST_DIR%
 CALL 7z a browser-source-%APPVEYOR_BUILD_NUMBER%.zip %DIST_SRC_DIR%\*
 cd %APPVEYOR_BUILD_FOLDER%