diff --git a/securedrop_client/gui/widgets.py b/securedrop_client/gui/widgets.py
index bc4f040f6..045c996df 100644
--- a/securedrop_client/gui/widgets.py
+++ b/securedrop_client/gui/widgets.py
@@ -1605,6 +1605,9 @@ def __init__(self, parent):
         self.parent = parent
         super().__init__(self.parent)
 
+        # Set modal
+        self.setModal(True)
+
         # Set css id
         self.setObjectName('login_dialog')