diff --git a/src/main.rs b/src/main.rs
index a20908a..e2ead9a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -538,6 +538,11 @@ fn make_box_tab(dbox: &DBox, window: &ApplicationWindow, tab_num: u32) -> gtk::B
     let win_clone = window.clone();
     delete_row.connect_activated(move |_row| on_delete_clicked(&win_clone, del_bn_clone.clone()));
 
+    // Deleting a running box would pull it out from under whatever is using it,
+    // so make the user stop it first. The Stop button on the header is right
+    // there while the box is up; once it is down the row enables itself.
+    delete_row.set_sensitive(!dbox.is_running);
+
     // Clone Box Icon
     let clone_icon = gtk::Image::from_icon_name(&get_available_icon_name(COPY_ICON_NAMES));