diff --git a/Tools/gulp/gulp-regenerate-expected.js b/Tools/gulp/gulp-regenerate-expected.js
index 25523c12ced30..10b848c1a71ba 100644
--- a/Tools/gulp/gulp-regenerate-expected.js
+++ b/Tools/gulp/gulp-regenerate-expected.js
@@ -9,7 +9,7 @@ var PluginError = gutil.PluginError;
 
 var isWindows = (process.platform.lastIndexOf('win') === 0);
 var isLinux= (process.platform.lastIndexOf('linux') === 0);
-var isMac = (process.platform.lastIndexOf('mac') === 0);
+var isMac = (process.platform.lastIndexOf('darwin') === 0);
 
 function GetAutoRestFolder() {
   if (isWindows) {
diff --git a/gulpfile.js b/gulpfile.js
index fcfd6a15e6afb..d2a58793c343c 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -24,7 +24,7 @@ const DEFAULT_ASSEMBLY_VERSION = '0.9.0.0';
 const MAX_BUFFER = 1024 * 4096;
 var isWindows = (process.platform.lastIndexOf('win') === 0);
 var isLinux= (process.platform.lastIndexOf('linux') === 0);
-var isMac = (process.platform.lastIndexOf('mac') === 0);
+var isMac = (process.platform.lastIndexOf('darwin') === 0);
 
 process.env.MSBUILDDISABLENODEREUSE = 1;