diff --git a/src/lint/linter/ArcanistPhutilLibraryLinter.php b/src/lint/linter/ArcanistPhutilLibraryLinter.php
index 0e9ca2b3..baee3ba3 100644
--- a/src/lint/linter/ArcanistPhutilLibraryLinter.php
+++ b/src/lint/linter/ArcanistPhutilLibraryLinter.php
@@ -1,233 +1,229 @@
 <?php
 
 /**
  * Applies lint rules for Phutil libraries. We enforce three rules:
  *
  *   # If you use a symbol, it must be defined somewhere.
  *   # If you define a symbol, it must not duplicate another definition.
  *   # If you define a class or interface in a file, it MUST be the only symbol
  *     defined in that file.
  */
 final class ArcanistPhutilLibraryLinter extends ArcanistLinter {
 
   const LINT_UNKNOWN_SYMBOL      = 1;
   const LINT_DUPLICATE_SYMBOL    = 2;
   const LINT_ONE_CLASS_PER_FILE  = 3;
 
   public function getInfoName() {
     return 'Phutil Library Linter';
   }
 
   public function getInfoDescription() {
     return pht(
       'Make sure all the symbols used in a %s library are defined and known. '.
       'This linter is specific to PHP source in %s libraries.',
       'libphutil',
       'libphutil');
   }
 
   public function getLinterName() {
     return 'PHL';
   }
 
   public function getLinterConfigurationName() {
     return 'phutil-library';
   }
 
   public function getCacheGranularity() {
     return self::GRANULARITY_GLOBAL;
   }
 
   public function getLintNameMap() {
     return array(
       self::LINT_UNKNOWN_SYMBOL      => pht('Unknown Symbol'),
       self::LINT_DUPLICATE_SYMBOL    => pht('Duplicate Symbol'),
       self::LINT_ONE_CLASS_PER_FILE  => pht('One Class Per File'),
     );
   }
 
   public function getLinterPriority() {
     return 2.0;
   }
 
   public function willLintPaths(array $paths) {
-    if (!xhpast_is_available()) {
-      throw new Exception(xhpast_get_build_instructions());
-    }
-
     // NOTE: For now, we completely ignore paths and just lint every library in
     // its entirety. This is simpler and relatively fast because we don't do any
     // detailed checks and all the data we need for this comes out of module
     // caches.
 
     $bootloader = PhutilBootloader::getInstance();
     $libraries  = $bootloader->getAllLibraries();
 
     // Load the up-to-date map for each library, without loading the library
     // itself. This means lint results will accurately reflect the state of
     // the working copy.
 
     $symbols = array();
 
     foreach ($libraries as $library) {
       $root = phutil_get_library_root($library);
 
       try {
         $symbols[$library] = id(new PhutilLibraryMapBuilder($root))
           ->buildFileSymbolMap();
       } catch (XHPASTSyntaxErrorException $ex) {
         // If the library contains a syntax error then there isn't much that we
         // can do.
         continue;
       }
     }
 
     $all_symbols = array();
     foreach ($symbols as $library => $map) {
       // Check for files which declare more than one class/interface in the same
       // file, or mix function definitions with class/interface definitions. We
       // must isolate autoloadable symbols to one per file so the autoloader
       // can't end up in an unresolvable cycle.
       foreach ($map as $file => $spec) {
         $have = idx($spec, 'have', array());
 
         $have_classes =
           idx($have, 'class', array()) +
           idx($have, 'interface', array());
         $have_functions = idx($have, 'function');
 
         if ($have_functions && $have_classes) {
           $function_list = implode(', ', array_keys($have_functions));
           $class_list = implode(', ', array_keys($have_classes));
           $this->raiseLintInLibrary(
             $library,
             $file,
             end($have_functions),
             self::LINT_ONE_CLASS_PER_FILE,
             pht(
               "File '%s' mixes function (%s) and class/interface (%s) ".
               "definitions in the same file. A file which declares a class ".
               "or an interface MUST declare nothing else.",
               $file,
               $function_list,
               $class_list));
         } else if (count($have_classes) > 1) {
           $class_list = implode(', ', array_keys($have_classes));
           $this->raiseLintInLibrary(
             $library,
             $file,
             end($have_classes),
             self::LINT_ONE_CLASS_PER_FILE,
             pht(
               "File '%s' declares more than one class or interface (%s). ".
               "A file which declares a class or interface MUST declare ".
               "nothing else.",
               $file,
               $class_list));
         }
       }
 
       // Check for duplicate symbols: two files providing the same class or
       // function.
       foreach ($map as $file => $spec) {
         $have = idx($spec, 'have', array());
         foreach (array('class', 'function', 'interface') as $type) {
           $libtype = ($type == 'interface') ? 'class' : $type;
           foreach (idx($have, $type, array()) as $symbol => $offset) {
             if (empty($all_symbols[$libtype][$symbol])) {
               $all_symbols[$libtype][$symbol] = array(
                 'library' => $library,
                 'file'    => $file,
                 'offset'  => $offset,
               );
               continue;
             }
 
             $osrc = $all_symbols[$libtype][$symbol]['file'];
             $olib = $all_symbols[$libtype][$symbol]['library'];
 
             $this->raiseLintInLibrary(
               $library,
               $file,
               $offset,
               self::LINT_DUPLICATE_SYMBOL,
               pht(
                 "Definition of %s '%s' in '%s' in library '%s' duplicates ".
                 "prior definition in '%s' in library '%s'.",
                 $type,
                 $symbol,
                 $file,
                 $library,
                 $osrc,
                 $olib));
           }
         }
       }
     }
 
     $types = array('class', 'function', 'interface', 'class/interface');
     foreach ($symbols as $library => $map) {
       // Check for unknown symbols: uses of classes, functions or interfaces
       // which are not defined anywhere. We reference the list of all symbols
       // we built up earlier.
       foreach ($map as $file => $spec) {
         $need = idx($spec, 'need', array());
         foreach ($types as $type) {
           $libtype = $type;
           if ($type == 'interface' || $type == 'class/interface') {
             $libtype = 'class';
           }
           foreach (idx($need, $type, array()) as $symbol => $offset) {
             if (!empty($all_symbols[$libtype][$symbol])) {
               // Symbol is defined somewhere.
               continue;
             }
 
             $libphutil_root = dirname(phutil_get_library_root('phutil'));
 
             $this->raiseLintInLibrary(
               $library,
               $file,
               $offset,
               self::LINT_UNKNOWN_SYMBOL,
               pht(
                 "Use of unknown %s '%s'. Common causes are:\n\n".
                 "  - Your %s is out of date.\n".
                 "    This is the most common cause.\n".
                 "    Update this copy of libphutil: %s\n\n".
                 "  - Some other library is out of date.\n".
                 "    Update the library this symbol appears in.\n\n".
                 "  - This symbol is misspelled.\n".
                 "    Spell the symbol name correctly.\n".
                 "    Symbol name spelling is case-sensitive.\n\n".
                 "  - This symbol was added recently.\n".
                 "    Run `%s` on the library it was added to.\n\n".
                 "  - This symbol is external. Use `%s`.\n".
                 "    Use `%s` to find usage examples of this directive.\n\n".
                 "*** ALTHOUGH USUALLY EASY TO FIX, THIS IS A SERIOUS ERROR.\n".
                 "*** THIS ERROR IS YOUR FAULT. YOU MUST RESOLVE IT.",
                 $type,
                 $symbol,
                 'libphutil/',
                 $libphutil_root,
                 'arc liberate',
                 '@phutil-external-symbol',
                 'grep'));
           }
         }
       }
     }
   }
 
   private function raiseLintInLibrary($library, $path, $offset, $code, $desc) {
     $root = phutil_get_library_root($library);
 
     $this->activePath = $root.'/'.$path;
     $this->raiseLintAtOffset($offset, $code, $desc);
   }
 
   public function lintPath($path) {
     return;
   }
 
 }