diff --git a/src/Inventory/Services/InventoryBaseService.php b/src/Inventory/Services/InventoryBaseService.php
index 862121f7ff..8bbf452156 100644
--- a/src/Inventory/Services/InventoryBaseService.php
+++ b/src/Inventory/Services/InventoryBaseService.php
@@ -40,6 +40,8 @@ public function __construct(array $config)
     public static function getConfigDefinitions()
     {
         $definitions = parent::getConfigDefinitions();
+        $definitions['requestLanguage']['default'] = 'en-US';
+        $definitions['requestLanguage']['required'] = true;
 
         return $definitions + [
             'apiVersion' => [
@@ -53,7 +55,7 @@ public static function getConfigDefinitions()
             ],
             'marketplaceId' => [
                 'valid' => ['string']
-            ]
+            ],
         ];
     }
 
diff --git a/test/Inventory/Services/ServiceTest.php b/test/Inventory/Services/ServiceTest.php
index 76ebd34585..f22cc2ad2d 100644
--- a/test/Inventory/Services/ServiceTest.php
+++ b/test/Inventory/Services/ServiceTest.php
@@ -29,6 +29,12 @@ public function testConfigDefinitions()
         $this->assertEquals([
             'valid' => ['string']
         ], $d['marketplaceId']);
+        $this->assertArrayHasKey('requestLanguage', $d);
+        $this->assertEquals([
+            'valid' => ['string'],
+            'default' => 'en-US',
+            'required' => true
+        ], $d['requestLanguage']);
     }
 
     public function testRequiredEbayHeaders()