diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index de46f5697910d8585d757890c0fc106d7d879688..3b2dadf9d2dbcd75a11cb73e7c2050cb3177894c 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -822,7 +822,7 @@ class installer_base {
 			}
 			$postfix_service = @($out[0]=='')?false:true;
         } else { //* fallback - Postfix < 2.9
-			rf($conf['postfix']['config_dir'].'/master.cf');
+			$content = rf($conf['postfix']['config_dir'].'/master.cf');
 			$regex = '/[^#]'.$service.'.*.'.$type.'.*/';
 			$postfix_service = @(!preg_match($regex, $content))?true:false;
 		}