diff --git a/classes/phing/system/io/YamlFileParser.php b/classes/phing/system/io/YamlFileParser.php
index 23d2dfeabe..6cbcbc7959 100644
--- a/classes/phing/system/io/YamlFileParser.php
+++ b/classes/phing/system/io/YamlFileParser.php
@@ -38,6 +38,14 @@ public function parseFile(PhingFile $file)
         }
 
         try {
+            
+            if (!class_exists('\Symfony\Component\Yaml\Parser')) {
+                throw new BuildException(
+                    get_class($this)
+                    . ' depends on \Symfony\Component\Yaml\Parser '
+                    . 'being installed and on include_path.'
+                );
+            }
             // We load the Yaml class without the use of namespaces to prevent
             // parse errors in PHP 5.2.
             $parserClass = '\Symfony\Component\Yaml\Parser';