diff --git a/Casks/decitime.rb b/Casks/decitime.rb
index e3f5f81d2..99a7f09cc 100644
--- a/Casks/decitime.rb
+++ b/Casks/decitime.rb
@@ -10,7 +10,7 @@ class Decitime < Cask
 
   # fix wonky DMG by mounting it once read-write per discussion at
   # https://github.com/caskroom/homebrew-cask/pull/2654
-  before_install do
+  preflight do
     system %Q{/usr/bin/hdiutil eject "$(/usr/bin/hdiutil mount -readwrite -noidme -nobrowse -mountrandom /tmp #{destination_path.join(artifacts[:nested_container].first)} | /usr/bin/cut -f3 -- - | /usr/bin/grep -- '.' -)" >/dev/null 2>&1}
   end
 end