diff --git a/aegisub/tools/osx-dmg.sh b/aegisub/tools/osx-dmg.sh
index 25d94c997..da596ddbb 100755
--- a/aegisub/tools/osx-dmg.sh
+++ b/aegisub/tools/osx-dmg.sh
@@ -64,7 +64,7 @@ echo "--- Generating /Volumes/${PKG_NAME_VOLUME}/.DS_Store ----"
 
 echo
 echo "---- Detaching ----"
-/usr/bin/hdiutil detach "${DEV_NAME}" || exit $?
+/usr/bin/hdiutil detach "${DEV_NAME}" -force || exit $?
 
 echo
 echo "---- Compressing ----"