diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index d1bcedfa71..00d7a3ea0b 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -532,7 +532,7 @@ function drupal_get_filename($type, $name, $filename = NULL) {
     // Fallback to searching the filesystem if the database connection is
     // not established or the requested file is not found.
     $config = conf_path();
-    $dir = (($type == 'theme_engine') ? 'themes/engines' : "${type}s");
+    $dir = (($type == 'theme_engine') ? 'themes/engines' : "{$type}s");
     $file = (($type == 'theme_engine') ? "$name.engine" : "$name.$type");
 
     foreach (array("$config/$dir/$file", "$config/$dir/$name/$file", "$dir/$file", "$dir/$name/$file") as $file) {