diff --git a/src/Services/HostedService.php b/src/Services/HostedService.php
index 113136b..74f02b7 100644
--- a/src/Services/HostedService.php
+++ b/src/Services/HostedService.php
@@ -141,12 +141,12 @@ public function parseResponse($response, $encoded = false)
             $response = $this->mapTransactionStatusResponse($response);
         }
 
-        $timestamp = $response["TIMESTAMP"];
-        $merchantId = $response["MERCHANT_ID"];
-        $orderId = $response["ORDER_ID"];
-        $result = $response["RESULT"];
-        $message = $response["MESSAGE"];
-        $transactionId = $response["PASREF"];
+        $timestamp = $response["TIMESTAMP"] ?? "";
+        $merchantId = $response["MERCHANT_ID"] ?? "";
+        $orderId = $response["ORDER_ID"] ?? "";
+        $result = $response["RESULT"] ?? "";
+        $message = $response["MESSAGE"] ?? "";
+        $transactionId = $response["PASREF"] ?? "";
         $authCode = $response["AUTHCODE"] ?? "";
         $paymentMethod = $response["PAYMENTMETHOD"] ?? "";
 
diff --git a/test/Integration/Gateways/GpEcomConnector/HppTest.php b/test/Integration/Gateways/GpEcomConnector/HppTest.php
index bc19e54..56062b2 100644
--- a/test/Integration/Gateways/GpEcomConnector/HppTest.php
+++ b/test/Integration/Gateways/GpEcomConnector/HppTest.php
@@ -1099,6 +1099,30 @@ public function testProcessPaymentConsumeResponse()
         $this->assertEquals("00", $responseCode);
     }
 
+    public function testParseResponseWithoutUppercaseKeysDoesNotWarn()
+    {
+        $service = new HostedService($this->config());
+
+        $response = [];
+        $response["SHA1HASH"] = GenerationUtils::generateNewHash(
+            "secret",
+            implode('.', ["", "", "", "", "", "", ""]),
+            ShaHashType::SHA1
+        );
+
+        set_error_handler(function ($errno, $errstr) {
+            throw new \ErrorException($errstr);
+        });
+        try {
+            $parsedResponse = $service->parseResponse(json_encode($response));
+        } finally {
+            restore_error_handler();
+        }
+
+        $this->assertNotNull($parsedResponse);
+        $this->assertEquals("", $parsedResponse->responseCode);
+    }
+
     /* 06. CardStorageCreatePayerStoreCardResponse */
 
     public function testCardStorageCreatePayerStoreCardResponse()