diff --git a/data/ui/source-dialog.ui b/data/ui/source-dialog.ui
index 83b68336..151fc9c3 100644
--- a/data/ui/source-dialog.ui
+++ b/data/ui/source-dialog.ui
@@ -267,6 +267,7 @@
             <property name="label" translatable="yes">Add</property>
             <property name="visible">True</property>
             <property name="can_focus">True</property>
+            <property name="sensitive">False</property>
             <property name="receives_default">True</property>
             <signal name="clicked" handler="action_widget_activated" object="GcalSourceDialog" swapped="no"/>
           </object>