diff --git a/Contrib/BgImage/BgImage.txt b/Contrib/BgImage/BgImage.txt
index 6650c422..70185700 100644
--- a/Contrib/BgImage/BgImage.txt
+++ b/Contrib/BgImage/BgImage.txt
@@ -23,6 +23,7 @@ Notes
 * This plugin requires NSIS 2.42 and above.
 
 * Do not call SetBg (which creates the window) from a section or a function called by a section.
+   BgImge must be run from the GUI thread as the installation thread is not built to handle GUI.
 
 Available functions
 ~~~~~~~~~~~~~~