diff --git a/lib/adminlib.php b/lib/adminlib.php
index a42016998fd..d6971734809 100644
--- a/lib/adminlib.php
+++ b/lib/adminlib.php
@@ -7312,8 +7312,10 @@ class admin_setting_configcolourpicker extends admin_setting {
                 $data = '#'.$data;
             }
             return $data;
-        } else if (preg_match('/^[a-zA-Z]{3, 25}$/')) {
+        } else if (preg_match('/^[a-zA-Z]{3, 25}$/', $data)) {
             return $data;
+        } else if (empty($data)) {
+            return null;
         } else {
             return false;
         }