diff --git a/Src/Common/SimpleRootSite/SimpleRootSite.cs b/Src/Common/SimpleRootSite/SimpleRootSite.cs
index 4a5adbfeaf..e4a2599848 100644
--- a/Src/Common/SimpleRootSite/SimpleRootSite.cs
+++ b/Src/Common/SimpleRootSite/SimpleRootSite.cs
@@ -1046,7 +1046,7 @@ private void RefreshIfNecessary(object sender, EventArgs e)
 			if (Visible)
 			{
 #pragma warning disable 618 // suppress obsolete warning
-				m_mediator.PostMessage("MasterRefresh", null);
+				m_mediator?.PostMessage("MasterRefresh", null);
 #pragma warning restore 618
 			}
 		}