diff --git a/tools/osx/INSTALL.readme.rtf b/tools/osx/INSTALL.readme.rtf
index 7d4aa060e..bffc9bae5 100644
--- a/tools/osx/INSTALL.readme.rtf
+++ b/tools/osx/INSTALL.readme.rtf
@@ -2,6 +2,8 @@ To install the RawTherapee application:
 
 1. Open the RawTherapee .dmg Disk Image included alongside this document.
 2. Drag the RawTherapee icon onto /Applications.
+3. If RawTherapee.app exists, click Replace in the dialog.
+4. Do not move or rename RawTherapee.app
 
 Note: For security reasons, RawTherapee MUST be installed in /Applications. RawTherapee will refuse to start if installed elsewhere.