diff --git a/scripts/build_xhpast.sh b/scripts/build_xhpast.php
similarity index 100%
rename from scripts/build_xhpast.sh
rename to scripts/build_xhpast.php
diff --git a/src/parser/xhpast/bin/PhutilXHPASTBinary.php b/src/parser/xhpast/bin/PhutilXHPASTBinary.php
index 5557621..ef0f3f2 100644
--- a/src/parser/xhpast/bin/PhutilXHPASTBinary.php
+++ b/src/parser/xhpast/bin/PhutilXHPASTBinary.php
@@ -1,134 +1,134 @@
 <?php
 
 final class PhutilXHPASTBinary {
 
   /**
    * The expected XHPAST version.
    *
    * This is the version that would be obtained with an up-to-date XHPAST
    * build. The //actual// XHPAST build version may vary.
    */
   const EXPECTED_VERSION = '5.5.8/1h';
 
   /**
    * The XHPAST build version.
    *
    * Cache the result from @{method:getVersion} to prevent excessive calls to
    * @{function:execx}.
    */
   private static $version;
 
   /**
    * Builds XHPAST automatically.
    *
    * Attempts to build the XHPAST binary automatically.
    *
    * @return void
    */
   public static function build() {
     if (Filesystem::binaryExists('gmake')) {
       $command = 'gmake';
     } else {
       $command = 'make';
     }
 
     $root = phutil_get_library_root('phutil');
     $path = Filesystem::resolvePath($root.'/../support/xhpast');
 
     // Run the build.
     execx(
       '%s -C %s %Ls',
       $command,
       $path,
       array('clean', 'all', 'install'));
 
     // Test the binary.
     if (!self::isAvailable()) {
       throw new Exception(pht('%s is broken.', 'xhpast'));
     }
 
     self::$version = null;
   }
 
   /**
    * Returns human-readable instructions for building XHPAST.
    *
    * @return string
    */
   public static function getBuildInstructions() {
     $root = phutil_get_library_root('phutil');
-    $make = Filesystem::resolvePath($root.'/../scripts/build_xhpast.sh');
+    $make = Filesystem::resolvePath($root.'/../scripts/build_xhpast.php');
 
     return phutil_console_format(
       "%s:\n\n  \$ %s\n",
       pht(
         "Your version of '%s' is unbuilt or out of date. Run this ".
         "script to build it.",
         'xhpast'),
       $make);
   }
 
   /**
    * Constructs an @{class:ExecFuture} for XHPAST.
    *
    * @param  wild        Data to pass to the future.
    * @return ExecFuture
    */
   public static function getParserFuture($data) {
     if (!self::isAvailable()) {
       try {
         // Try to build XHPAST automatically. If we can't then just ask the
         // user to build it themselves.
         self::build();
       } catch (CommandException $ex) {
         throw new PhutilProxyException(self::getBuildInstructions(), $ex);
       }
     }
     $future = new ExecFuture('%s', self::getPath());
     $future->write($data);
 
     return $future;
   }
 
   /**
    * Returns the path to the XHPAST binary.
    *
    * @return string
    */
   public static function getPath() {
     if (phutil_is_windows()) {
       return dirname(__FILE__).'\\xhpast.exe';
     }
     return dirname(__FILE__).'/xhpast';
   }
 
   /**
    * Returns the XHPAST version.
    *
    * @return string
    */
   public static function getVersion() {
     if (self::$version === null) {
       $bin = self::getPath();
 
       if (Filesystem::pathExists($bin)) {
         list($err, $stdout) = exec_manual('%s --version', $bin);
         if (!$err) {
           self::$version = trim($stdout);
         }
       }
     }
 
     return self::$version;
   }
 
   /**
    * Checks if XHPAST is built and up-to-date.
    *
    * @return bool
    */
   public static function isAvailable() {
     return self::getVersion() == self::EXPECTED_VERSION;
   }
 
 }