diff --git a/core/core-ui.el b/core/core-ui.el
index 1ac441088..37e4fda6a 100644
--- a/core/core-ui.el
+++ b/core/core-ui.el
@@ -138,8 +138,8 @@ size.")
 e.g. If you indent with spaces by default, tabs will be highlighted. If you
 indent with tabs, spaces at BOL are highlighted.
 
-Does nothing if `whitespace-mode' is already active or the current buffer is
-read-only or not file-visiting."
+Does nothing if `whitespace-mode' or 'global-whitespace-mode'is already 
+active or if the current buffer is read-only or not file-visiting."
   (unless (or (eq major-mode 'fundamental-mode)
               buffer-read-only
               (equal global-whitespace-mode t)