diff --git a/tests/upgrade_preinstall.pm b/tests/upgrade_preinstall.pm
index ebaf12ea..0a769139 100644
--- a/tests/upgrade_preinstall.pm
+++ b/tests/upgrade_preinstall.pm
@@ -26,7 +26,7 @@ sub run {
     assert_script_run $update_command, 600;
 }
 
-if (get_var("ASSUME_BOOT") == 1) {
+if (get_var("ASSUME_BOOT",0) == 1) {
     desktop_vt;
 }