diff --git a/Model/Api/Base.php b/Model/Api/Base.php
index a0ad9ad..0e48913 100644
--- a/Model/Api/Base.php
+++ b/Model/Api/Base.php
@@ -82,10 +82,10 @@ public function sendRequest($data, $cmd, $headers = [], $method = 'post', $assoc
     {
         $paymentConf = $this->getPaymentConfig();
         $baseConf = $this->getBaseConfig();
-        
+
         $paymentConf['public_key'] = isset($paymentConf['public_key']) ? $paymentConf['public_key'] : '';
         $paymentConf['api_version'] = isset($paymentConf['api_version']) ? $paymentConf['api_version'] : '1';
-        
+
         $additionalData = [
             'version' => $baseConf['api_version'],
             'cmd' => $cmd,
@@ -112,7 +112,7 @@ public function sendRequest($data, $cmd, $headers = [], $method = 'post', $assoc
     public function generateHmac($data, $secretKey = null)
     {
         if (!$secretKey) {
-            $secretKey = $this->getPaymentConfig('secret_key');
+            $secretKey = $this->getPaymentConfig('secret_key') ?: '';
         }
         return hash_hmac('sha512', http_build_query($data), $secretKey);
     }
diff --git a/Model/CoinPaymentsConfigProvider.php b/Model/CoinPaymentsConfigProvider.php
index 19cda93..9806ec7 100644
--- a/Model/CoinPaymentsConfigProvider.php
+++ b/Model/CoinPaymentsConfigProvider.php
@@ -68,22 +68,27 @@ public function getConfig()
         $this->_curl->post($coinpaymentsApi, $data);
         $response = json_decode($this->_curl->getBody());
 
-        $currencies = ['error' => $response->error];
-        $acceptedCurrencies = ['error' => $response->error];
-        if ($response->error == 'ok') {
-            $currencies = [];
-            $acceptedCurrencies = [];
-            foreach ($response->result as $key => $item) {
-                $elm = [
-                    'value' => $key,
-                    'body' => $item,
-                    'name' => $item->name
-                ];
-                $currencies[] = $elm;
-                if (isset($item->accepted) && $item->accepted == '1') {
-                    $acceptedCurrencies[] = $elm;
+        if (!is_null($response) && property_exists($response, 'error') && property_exists($response, 'result')) {
+            $currencies = ['error' => $response->error];
+            $acceptedCurrencies = ['error' => $response->error];
+            if ($response->error == 'ok') {
+                $currencies = [];
+                $acceptedCurrencies = [];
+                foreach ($response->result as $key => $item) {
+                    $elm = [
+                        'value' => $key,
+                        'body' => $item,
+                        'name' => $item->name
+                    ];
+                    $currencies[] = $elm;
+                    if (isset($item->accepted) && $item->accepted == '1') {
+                        $acceptedCurrencies[] = $elm;
+                    }
                 }
             }
+        } else {
+            $currencies = ['error' => 'Could not load currencies list.'];
+            $acceptedCurrencies = ['error' => 'Could not load currencies list.'];
         }
 
         return [
diff --git a/composer.json b/composer.json
index 4c3ba09..3275085 100644
--- a/composer.json
+++ b/composer.json
@@ -2,10 +2,10 @@
   "name": "coinpaymentsnet/magento2",
   "description": "Add new payment method for CoinPayments.net",
   "require": {
-    "php": "~5.5.0|~5.6.0|~7.0.0|~7.1"
+    "php": "~5.5.0|~5.6.0|~7.0.0|~7.1|~8.0|~8.1"
   },
   "type": "magento2-module",
-  "version": "1.6.0",
+  "version": "1.6.2",
   "license": [
     "OSL-3.0"
   ],
diff --git a/view/frontend/templates/coinpayments/iframe.phtml b/view/frontend/templates/coinpayments/iframe.phtml
index 7a98c57..8714a38 100644
--- a/view/frontend/templates/coinpayments/iframe.phtml
+++ b/view/frontend/templates/coinpayments/iframe.phtml
@@ -26,8 +26,8 @@ $failUrl     = $block->getFailUrl();
         'utf-8'
     ); ?>">
     <input type="hidden" name="shippingf" value="<?php echo $block->getShippingAmount(); ?>">
-    <input type="hidden" name="taxf" value="<?php $quoteData->getShippingAddress()->getTaxAmount(); ?>">
-    <input type="hidden" name="amountf" value="<?php echo $quoteData->getSubtotal(); ?>">
+    <input type="hidden" name="taxf" value="<?php echo $quoteData->getShippingAddress()->getTaxAmount(); ?>">
+    <input type="hidden" name="amountf" value="<?php echo $quoteData->getSubtotalWithDiscount(); ?>">
     <input type="hidden" name="success_url" value="<?php echo $successUrl; ?>">
     <input type="hidden" name="cancel_url" value="<?php echo $failUrl; ?>">
     <input type="hidden" name="ipn_url" value="<?php echo htmlspecialchars($block->getIpnUrl(), ENT_QUOTES, 'utf-8'); ?>">
@@ -50,4 +50,4 @@ $failUrl     = $block->getFailUrl();
 </form>
 <script type="text/javascript">
     document.coinpaymentsform.submit();
-</script>
\ No newline at end of file
+</script>