diff --git a/app/email_queue/resources/service/email_queue.php b/app/email_queue/resources/service/email_queue.php
index 9d766c86e3..7922501b0a 100644
--- a/app/email_queue/resources/service/email_queue.php
+++ b/app/email_queue/resources/service/email_queue.php
@@ -58,7 +58,7 @@
 		$exists = false;
 
 		//check to see if the process is running
-		if (file_exists($file)) {
+		if (function_exists(posix_getsid) && file_exists($file)) {
 			$pid = file_get_contents($file);
 			if (posix_getsid($pid) === false) { 
 				//process is not running