diff --git a/src/filesystem/binary/PhutilMercurialBinaryAnalyzer.php b/src/filesystem/binary/PhutilMercurialBinaryAnalyzer.php
index 4edbfd1..02dbde0 100644
--- a/src/filesystem/binary/PhutilMercurialBinaryAnalyzer.php
+++ b/src/filesystem/binary/PhutilMercurialBinaryAnalyzer.php
@@ -1,77 +1,83 @@
 <?php
 
 final class PhutilMercurialBinaryAnalyzer
   extends PhutilBinaryAnalyzer {
 
   const BINARY = 'hg';
 
   const CAPABILITY_FILES = 'files';
   const CAPABILITY_INJECTION = 'injection';
 
   protected function newBinaryVersion() {
-    list($err, $stdout) = exec_manual('hg --version --quiet');
+    $future = id(new ExecFuture('hg --version --quiet'))
+      ->setEnv(
+        array(
+          'HGPLAIN' => 1,
+        ));
+
+    list($err, $stdout) = $future->resolve();
 
     if ($err) {
       return null;
     }
 
     return self::parseMercurialBinaryVersion($stdout);
   }
 
   public static function parseMercurialBinaryVersion($stdout) {
     // NOTE: At least on OSX, recent versions of Mercurial report this
     // string in this format:
     //
     //   Mercurial Distributed SCM (version 3.1.1+20140916)
 
     $matches = null;
     $pattern = '/^Mercurial Distributed SCM \(version ([\d.]+)/m';
     if (preg_match($pattern, $stdout, $matches)) {
       return $matches[1];
     }
 
     return null;
   }
 
   /**
    * The `locate` command is deprecated as of Mercurial 3.2, to be replaced
    * with `files` command, which supports most of the same arguments. This
    * determines whether the new `files` command should be used instead of
    * the `locate` command.
    *
    * @return boolean  True if the version of Mercurial is new enough to support
    *   the `files` command, or false if otherwise.
    */
   public function isMercurialFilesCommandAvailable() {
     return self::versionHasCapability(
       $this->requireBinaryVersion(),
       self::CAPABILITY_FILES);
   }
 
   public function isMercurialVulnerableToInjection() {
     return self::versionHasCapability(
       $this->requireBinaryVersion(),
       self::CAPABILITY_INJECTION);
   }
 
 
   public static function versionHasCapability(
     $mercurial_version,
     $capability) {
 
     switch ($capability) {
       case self::CAPABILITY_FILES:
         return version_compare($mercurial_version, '3.2', '>=');
       case self::CAPABILITY_INJECTION:
         return version_compare($mercurial_version, '3.2.4', '<');
       default:
         throw new Exception(
           pht(
             'Unknown Mercurial capability "%s".',
             $capability));
     }
 
   }
 
 
 }