diff --git a/src/Stagehand/TestRunner/Collector.php b/src/Stagehand/TestRunner/Collector.php
index <HASH>..<HASH> 100644
--- a/src/Stagehand/TestRunner/Collector.php
+++ b/src/Stagehand/TestRunner/Collector.php
@@ -212,7 +212,7 @@ abstract class Stagehand_TestRunner_Collector
      */
     protected function collectTestCasesFromFile($file)
     {
-        if (!preg_match("/{$this->suffix}\.php\$/", $file)) {
+        if (!preg_match('/' . $this->suffix . '\.php$/', $file)) {
             return;
         }
Moved a variable to outside of double quotes.