diff --git a/Casks/readitall.rb b/Casks/readitall.rb
index 3965f7f..8ef291a 100644
--- a/Casks/readitall.rb
+++ b/Casks/readitall.rb
@@ -33,10 +33,9 @@ cask "readitall" do
 
   binary "readitall"
 
-  postflight do
-    if OS.mac?
-      system_command "/usr/bin/xattr",
-                     args: ["-dr", "com.apple.quarantine", "#{staged_path}/readitall"]
+  postflight_steps do
+    on_macos do
+      run "/usr/bin/xattr", args: ["-dr", "com.apple.quarantine", "{{staged_path}}/readitall"]
     end
   end
 
diff --git a/Casks/semver-generator.rb b/Casks/semver-generator.rb
index 7b4cc2e..14ac4cc 100644
--- a/Casks/semver-generator.rb
+++ b/Casks/semver-generator.rb
@@ -33,10 +33,9 @@ cask "semver-generator" do
 
   binary "semver-generator"
 
-  postflight do
-    if OS.mac?
-      system_command "/usr/bin/xattr",
-                     args: ["-dr", "com.apple.quarantine", "#{staged_path}/semver-generator"]
+  postflight_steps do
+    on_macos do
+      run "/usr/bin/xattr", args: ["-dr", "com.apple.quarantine", "{{staged_path}}/semver-generator"]
     end
   end