diff --git a/src/xsprintf/PhutilCommandString.php b/src/xsprintf/PhutilCommandString.php
--- a/src/xsprintf/PhutilCommandString.php
+++ b/src/xsprintf/PhutilCommandString.php
@@ -11,7 +11,7 @@
   public function __construct(array $argv) {
     $this->argv = $argv;
 
-    $this->escapingMode = self::MODE_DEFAULT;
+    $this->escapingMode = phutil_is_windows() ? self::MODE_POWERSHELL : self::MODE_DEFAULT;
 
     // This makes sure we throw immediately if there are errors in the
     // parameters.