diff --git a/Library/Homebrew/unpack_strategy/dmg.rb b/Library/Homebrew/unpack_strategy/dmg.rb
index 085eec6176..a792255ecc 100644
--- a/Library/Homebrew/unpack_strategy/dmg.rb
+++ b/Library/Homebrew/unpack_strategy/dmg.rb
@@ -29,7 +29,7 @@ module UnpackStrategy
 
         # symlinks to system directories (commonly to /Applications)
         def system_dir_symlink?
-          symlink? && MacOS.system_dir?(readlink)
+          symlink? && MacOS.system_dir?(realpath)
         end
 
         def bom