diff --git a/Casks/harness-sync.rb b/Casks/harness-sync.rb
index 7a1441a..01f15e4 100644
--- a/Casks/harness-sync.rb
+++ b/Casks/harness-sync.rb
@@ -33,10 +33,9 @@ cask "harness-sync" do
 
   binary "harness-sync"
 
-  postflight do
-    if OS.mac?
-      system_command "/usr/bin/xattr",
-                     args: ["-dr", "com.apple.quarantine", "#{staged_path}/harness-sync"]
+  postflight_steps do
+    on_macos do
+      run "/usr/bin/xattr", args: ["-dr", "com.apple.quarantine", "{{staged_path}}/harness-sync"]
     end
   end
 
diff --git a/Casks/kportal.rb b/Casks/kportal.rb
index 0d6199f..8c2e0a8 100644
--- a/Casks/kportal.rb
+++ b/Casks/kportal.rb
@@ -33,10 +33,9 @@ cask "kportal" do
 
   binary "kportal"
 
-  postflight do
-    if OS.mac?
-      system_command "/usr/bin/xattr",
-                     args: ["-dr", "com.apple.quarantine", "#{staged_path}/kportal"]
+  postflight_steps do
+    on_macos do
+      run "/usr/bin/xattr", args: ["-dr", "com.apple.quarantine", "{{staged_path}}/kportal"]
     end
   end
 
diff --git a/Casks/lolcathost.rb b/Casks/lolcathost.rb
index 246800d..f927129 100644
--- a/Casks/lolcathost.rb
+++ b/Casks/lolcathost.rb
@@ -33,10 +33,9 @@ cask "lolcathost" do
 
   binary "lolcathost"
 
-  postflight do
-    if OS.mac?
-      system_command "/usr/bin/xattr",
-                     args: ["-dr", "com.apple.quarantine", "#{staged_path}/lolcathost"]
+  postflight_steps do
+    on_macos do
+      run "/usr/bin/xattr", args: ["-dr", "com.apple.quarantine", "{{staged_path}}/lolcathost"]
     end
   end
 
diff --git a/Casks/semver-generator.rb b/Casks/semver-generator.rb
index dd64868..9e8765b 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