diff --git a/lib/common-functions b/lib/common-functions
index 0343a0c12..ead477a34 100644
--- a/lib/common-functions
+++ b/lib/common-functions
@@ -145,7 +145,7 @@ function mount_qcow_image() {
 function cleanup_dirs () {
     sudo rm -rf $TMP_BUILD_DIR/built
     sudo rm -rf $TMP_BUILD_DIR/mnt
-    sudo umount $TMP_BUILD_DIR
+    sudo umount -f  $TMP_BUILD_DIR || true
     rm -rf $TMP_BUILD_DIR
 }