diff --git a/src/Mustache/Compiler.php b/src/Mustache/Compiler.php
index da634d3..f7091cc 100644
--- a/src/Mustache/Compiler.php
+++ b/src/Mustache/Compiler.php
@@ -410,9 +410,7 @@ class Mustache_Compiler
     {
         $block = '';
 
-        $real_children = array_filter($children, function($ch) {
-            return $ch[Mustache_Tokenizer::TYPE] == Mustache_Tokenizer::T_PARENT_ARG;
-        });
+        $real_children = array_filter($children, array(__CLASS__, 'return_only_parent_args'));
 
         $block = $this->walk($real_children, $level);
 
@@ -423,6 +421,11 @@ class Mustache_Compiler
         );
     }
 
+    private static function return_only_parent_args($child)
+    {
+        return $child[Mustache_Tokenizer::TYPE] == Mustache_Tokenizer::T_PARENT_ARG;
+    }
+
     const VARIABLE = '
         $value = $this->resolveValue($context->%s(%s), $context, $indent);%s
         $buffer .= %s%s;
diff --git a/vendor/spec b/vendor/spec
index bf6288e..7c3923d 160000
--- a/vendor/spec
+++ b/vendor/spec
@@ -1 +1 @@
-Subproject commit bf6288ed6bd0ce8ccea6f1dac070b3d779132c3b
+Subproject commit 7c3923d0079a345136325f7d1895f5d98efa9701