diff --git a/src/applications/diffusion/conduit/DiffusionQueryPathsConduitAPIMethod.php b/src/applications/diffusion/conduit/DiffusionQueryPathsConduitAPIMethod.php
index 5ca2783838..be2f07f2c6 100644
--- a/src/applications/diffusion/conduit/DiffusionQueryPathsConduitAPIMethod.php
+++ b/src/applications/diffusion/conduit/DiffusionQueryPathsConduitAPIMethod.php
@@ -1,103 +1,104 @@
 <?php
 
 final class DiffusionQueryPathsConduitAPIMethod
   extends DiffusionQueryConduitAPIMethod {
 
   public function getAPIMethodName() {
     return 'diffusion.querypaths';
   }
 
   public function getMethodDescription() {
     return pht('Filename search on a repository.');
   }
 
   protected function defineReturnType() {
     return 'list<string>';
   }
 
   protected function defineCustomParamTypes() {
     return array(
       'path' => 'required string',
       'commit' => 'required string',
       'pattern' => 'optional string',
       'limit' => 'optional int',
       'offset' => 'optional int',
     );
   }
 
   protected function getResult(ConduitAPIRequest $request) {
     $results = parent::getResult($request);
     $offset = $request->getValue('offset');
     return array_slice($results, $offset);
   }
 
   protected function getGitResult(ConduitAPIRequest $request) {
     $drequest = $this->getDiffusionRequest();
     $path = $drequest->getPath();
     $commit = $request->getValue('commit');
     $repository = $drequest->getRepository();
 
     // http://comments.gmane.org/gmane.comp.version-control.git/197735
 
     $future = $repository->getLocalCommandFuture(
       'ls-tree --name-only -r -z %s -- %s',
       $commit,
       $path);
 
     $lines = id(new LinesOfALargeExecFuture($future))->setDelimiter("\0");
     return $this->filterResults($lines, $request);
   }
 
   protected function getMercurialResult(ConduitAPIRequest $request) {
     $drequest = $this->getDiffusionRequest();
     $repository = $drequest->getRepository();
     $path = $request->getValue('path');
     $commit = $request->getValue('commit');
 
     $entire_manifest = id(new DiffusionLowLevelMercurialPathsQuery())
       ->setRepository($repository)
       ->withCommit($commit)
       ->withPath($path)
       ->execute();
 
     $match_against = trim($path, '/');
     $match_len = strlen($match_against);
 
     $lines = array();
     foreach ($entire_manifest as $path) {
       if (strlen($path) && !strncmp($path, $match_against, $match_len)) {
         $lines[] = $path;
       }
     }
 
     return $this->filterResults($lines, $request);
   }
 
   protected function filterResults($lines, ConduitAPIRequest $request) {
     $pattern = $request->getValue('pattern');
     $limit = (int)$request->getValue('limit');
     $offset = (int)$request->getValue('offset');
 
     if (strlen($pattern)) {
-      $pattern = '/'.preg_quote($pattern, '/').'/';
+      // Add delimiters to the regex pattern.
+      $pattern = '('.$pattern.')';
     }
 
     $results = array();
     $count = 0;
     foreach ($lines as $line) {
       if (strlen($pattern) && !preg_match($pattern, $line)) {
         continue;
       }
 
       $results[] = $line;
       $count++;
 
       if ($limit && ($count >= ($offset + $limit))) {
         break;
       }
     }
 
     return $results;
   }
 
 }