diff --git a/dangerzone/gui.py b/dangerzone/gui.py
index 0b2755d..6df9b4d 100644
--- a/dangerzone/gui.py
+++ b/dangerzone/gui.py
@@ -56,7 +56,9 @@ def gui_main(custom_container, filename):
 
     if custom_container:
         # Do we have this container?
-        with global_common.exec_dangerzone_container(["ls", custom_container]) as p:
+        with global_common.exec_dangerzone_container(
+            ["ls", "--container-name", custom_container]
+        ) as p:
             stdout_data, stderr_data = p.communicate()
 
             # The user canceled, or permission denied