diff --git a/WellnessLiving/Config/WlConfigAbstract.php b/WellnessLiving/Config/WlConfigAbstract.php
index 4f70fe5d..cb51eadb 100644
--- a/WellnessLiving/Config/WlConfigAbstract.php
+++ b/WellnessLiving/Config/WlConfigAbstract.php
@@ -86,7 +86,7 @@ abstract class WlConfigAbstract
    * @see \WellnessLiving\Config\WlConfigProduction
    * @see \WellnessLiving\Config\WlConfigDeveloper
    */
-  protected $REGION_URL=null;
+  protected static $REGION_URL=null;
 
   /**
    * List of rules, which is used to convert error codes to HTTP codes.
diff --git a/WellnessLiving/Config/WlConfigDeveloper.php b/WellnessLiving/Config/WlConfigDeveloper.php
index 16c9b890..646ad07f 100644
--- a/WellnessLiving/Config/WlConfigDeveloper.php
+++ b/WellnessLiving/Config/WlConfigDeveloper.php
@@ -27,7 +27,7 @@ abstract class WlConfigDeveloper extends WlConfigAbstract
   /**
    * @inheritDoc
    */
-  protected $REGION_URL = [
+  protected static $REGION_URL = [
     WlRegionSid::AP_SOUTHEAST_2 => 'https://demo.wellnessliving.com/',
     WlRegionSid::US_EAST_1 => 'https://staging.wellnessliving.com/',
   ];
diff --git a/WellnessLiving/Config/WlConfigProduction.php b/WellnessLiving/Config/WlConfigProduction.php
index 9987f196..a0518865 100644
--- a/WellnessLiving/Config/WlConfigProduction.php
+++ b/WellnessLiving/Config/WlConfigProduction.php
@@ -22,7 +22,7 @@ abstract class WlConfigProduction extends WlConfigAbstract
   /**
    * @inheritDoc
    */
-  protected $REGION_URL = [
+  protected static $REGION_URL = [
     WlRegionSid::AP_SOUTHEAST_2 => 'https://au.wellnessliving.com/',
     WlRegionSid::US_EAST_1 => 'https://us.wellnessliving.com/',
   ];