diff --git a/modules/ppcp-button/resources/js/modules/ActionHandler/CartActionHandler.js b/modules/ppcp-button/resources/js/modules/ActionHandler/CartActionHandler.js
index 0b8e5009c..00966ec6c 100644
--- a/modules/ppcp-button/resources/js/modules/ActionHandler/CartActionHandler.js
+++ b/modules/ppcp-button/resources/js/modules/ActionHandler/CartActionHandler.js
@@ -17,7 +17,7 @@ class CartActionHandler {
             return fetch(this.config.ajax.create_order.endpoint, {
                 method: 'POST',
                 headers: {
-                    "Content-Type": "application/json",
+                    'Content-Type': 'application/json'
                 },
                 credentials: 'same-origin',
                 body: JSON.stringify({
diff --git a/modules/ppcp-button/resources/js/modules/ActionHandler/CheckoutActionHandler.js b/modules/ppcp-button/resources/js/modules/ActionHandler/CheckoutActionHandler.js
index 0f330ca04..522880333 100644
--- a/modules/ppcp-button/resources/js/modules/ActionHandler/CheckoutActionHandler.js
+++ b/modules/ppcp-button/resources/js/modules/ActionHandler/CheckoutActionHandler.js
@@ -33,7 +33,7 @@ class CheckoutActionHandler {
             return fetch(this.config.ajax.create_order.endpoint, {
                 method: 'POST',
                 headers: {
-                    "Content-Type": "application/json",
+                    'Content-Type': 'application/json'
                 },
                 credentials: 'same-origin',
                 body: JSON.stringify({
diff --git a/modules/ppcp-button/resources/js/modules/ActionHandler/SingleProductActionHandler.js b/modules/ppcp-button/resources/js/modules/ActionHandler/SingleProductActionHandler.js
index 8e7057ff5..f1456a5b0 100644
--- a/modules/ppcp-button/resources/js/modules/ActionHandler/SingleProductActionHandler.js
+++ b/modules/ppcp-button/resources/js/modules/ActionHandler/SingleProductActionHandler.js
@@ -67,7 +67,7 @@ class SingleProductActionHandler {
                 return fetch(this.config.ajax.create_order.endpoint, {
                     method: 'POST',
                     headers: {
-                        "Content-Type": "application/json",
+                        'Content-Type': 'application/json'
                     },
                     credentials: 'same-origin',
                     body: JSON.stringify({
diff --git a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js
index 278a710ef..2068563a7 100644
--- a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js
+++ b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForContinue.js
@@ -3,7 +3,7 @@ const onApprove = (context, errorHandler) => {
         return fetch(context.config.ajax.approve_order.endpoint, {
             method: 'POST',
             headers: {
-                "Content-Type": "application/json",
+                'Content-Type': 'application/json'
             },
             credentials: 'same-origin',
             body: JSON.stringify({
diff --git a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js
index e1c634c4d..e8fcbde09 100644
--- a/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js
+++ b/modules/ppcp-button/resources/js/modules/OnApproveHandler/onApproveForPayNow.js
@@ -6,7 +6,7 @@ const onApprove = (context, errorHandler, spinner) => {
         return fetch(context.config.ajax.approve_order.endpoint, {
             method: 'POST',
             headers: {
-                "Content-Type": "application/json",
+                'Content-Type': 'application/json'
             },
             credentials: 'same-origin',
             body: JSON.stringify({