diff --git a/reference/filter/functions/filter-var.xml b/reference/filter/functions/filter-var.xml
index 12cfdee46e..246975931d 100644
--- a/reference/filter/functions/filter-var.xml
+++ b/reference/filter/functions/filter-var.xml
@@ -73,11 +73,15 @@ $var = filter_var('oops', FILTER_VALIDATE_BOOLEAN,
 function foo($value)
 {
     // Expected format: Surname, GivenNames
+    if (strpos($value, ", ") === false) return false;
     list($surname, $givennames) = explode(", ", $value, 2);
-    if(
-        !(empty($surname) || empty($givennames))
-        && (is_string($surname) && is_string($givennames))
-      ) return $value; else return false;
+    $empty = (empty($surname) || empty($givennames));
+    $notstrings = (!is_string($surname) || !is_string($givennames));
+    if ($empty || $notstrings) {
+        return false;
+    } else {
+        return $value;
+    }
 }
 $var = filter_var('Doe, Jane Sue', FILTER_CALLBACK, array('options' => 'foo'));
 ?>