diff --git a/Casks/game-porting-toolkit.rb b/Casks/game-porting-toolkit.rb
index 063be26..719da54 100644
--- a/Casks/game-porting-toolkit.rb
+++ b/Casks/game-porting-toolkit.rb
@@ -30,7 +30,7 @@
   binary "#{appdir}/Game Porting Toolkit.app/Contents/Resources/wine/bin/wineserver"
 
   postflight do
-    system "xattr", "-drs", "com.apple.quarantine", "#{appdir}/Game Porting Toolkit.app"
+    system_command "/usr/bin/xattr", args: ["-drs", "com.apple.quarantine", "#{appdir}/Game Porting Toolkit.app"], sudo: false
   end
 
   zap trash: [
diff --git a/Casks/portingkit.rb b/Casks/portingkit.rb
index 1051bb2..741cf11 100644
--- a/Casks/portingkit.rb
+++ b/Casks/portingkit.rb
@@ -10,7 +10,7 @@
   app "Porting kit.app"
 
   postflight do
-    system "xattr", "-drs", "com.apple.quarantine", "#{appdir}/Porting kit.app"
+    system_command "/usr/bin/xattr", args: ["-drs", "com.apple.quarantine", "#{appdir}/Porting kit.app"], sudo: false
   end
 
   caveats <<~EOS
diff --git a/Casks/wine-crossover.rb b/Casks/wine-crossover.rb
index 0aeb597..c2f0de5 100644
--- a/Casks/wine-crossover.rb
+++ b/Casks/wine-crossover.rb
@@ -40,7 +40,7 @@
   binary "#{appdir}/Wine Crossover.app/Contents/Resources/wine/bin/wineserver"
 
   postflight do
-    system "xattr", "-drs", "com.apple.quarantine", "#{appdir}/Wine Crossover.app"
+    system_command "/usr/bin/xattr", args: ["-drs", "com.apple.quarantine", "#{appdir}/Wine Crossover.app"], sudo: false
   end
 
   caveats <<~EOS
diff --git a/Casks/wineskin-devel.rb b/Casks/wineskin-devel.rb
index ee2d137..00ab958 100644
--- a/Casks/wineskin-devel.rb
+++ b/Casks/wineskin-devel.rb
@@ -14,11 +14,9 @@
 
   app "Wineskin Winery.app"
 
-  # Workaround issue until it's fixed in Winery
-  # https://github.com/Gcenx/WineskinServer/issues/96
   preflight do
-    system "xattr", "-drs", "com.apple.quarantine", "#{appdir}/Wineskin Winery.app"
     system_command "/bin/mkdir", args: ["-p", "/Users/#{ENV.fetch("USER")}/Applications/Wineskin"], sudo: false
+    system_command "/usr/bin/xattr", args: ["-drs", "com.apple.quarantine", "#{appdir}/Wineskin Winery.app"], sudo: false
   end
 
   zap trash: [
diff --git a/Casks/wineskin.rb b/Casks/wineskin.rb
index f4bb052..4fc8462 100644
--- a/Casks/wineskin.rb
+++ b/Casks/wineskin.rb
@@ -15,11 +15,9 @@
 
   app "Wineskin Winery.app"
 
-  # Workaround issue until it's fixed in Winery
-  # https://github.com/Gcenx/WineskinServer/issues/96
   preflight do
-    system "xattr", "-drs", "com.apple.quarantine", "#{appdir}/Wineskin Winery.app"
     system_command "/bin/mkdir", args: ["-p", "/Users/#{ENV.fetch("USER")}/Applications/Wineskin"], sudo: false
+    system_command "/usr/bin/xattr", args: ["-drs", "com.apple.quarantine", "#{appdir}/Wineskin Winery.app"], sudo: false
   end
 
   zap trash: [