diff --git a/src/Plugin/Preprocess/Region.php b/src/Plugin/Preprocess/Region.php
index 57991bb..2aa7d26 100644
--- a/src/Plugin/Preprocess/Region.php
+++ b/src/Plugin/Preprocess/Region.php
@@ -38,7 +38,7 @@ class Region extends PreprocessBase implements PreprocessInterface {
 
     // Support for "well" classes in regions.
     static $region_wells;
-    if (!isset($wells)) {
+    if (!isset($region_wells)) {
       $region_wells = $this->theme->getSetting('region_wells');
     }
     if (!empty($region_wells[$region])) {