diff --git a/libs/plugins/shared.make_timestamp.php b/libs/plugins/shared.make_timestamp.php
index 832488ba..f143aada 100644
--- a/libs/plugins/shared.make_timestamp.php
+++ b/libs/plugins/shared.make_timestamp.php
@@ -22,7 +22,7 @@ function smarty_make_timestamp($string)
         return time();
     } elseif ($string instanceof DateTime) {
         return $string->getTimestamp();
-    } elseif (preg_match('/^\d{14}$/', $string)) {
+    } elseif (ctype_digit($string) && strlen($string)==14) {
         // it is mysql timestamp format of YYYYMMDDHHMMSS?            
         return mktime(substr($string, 8, 2),substr($string, 10, 2),substr($string, 12, 2),
                        substr($string, 4, 2),substr($string, 6, 2),substr($string, 0, 4));
@@ -40,4 +40,4 @@ function smarty_make_timestamp($string)
     }
 }
 
-?>
\ No newline at end of file
+?>