diff --git a/src/renderer/constants/modal_types.js b/src/renderer/constants/modal_types.js
new file mode 100644
index 000000000..6e3bc67d6
--- /dev/null
+++ b/src/renderer/constants/modal_types.js
@@ -0,0 +1,23 @@
+export const CONFIRM_FILE_REMOVE = 'confirm_file_remove';
+export const INCOMPATIBLE_DAEMON = 'incompatible_daemon';
+export const FILE_TIMEOUT = 'file_timeout';
+export const DOWNLOADING = 'downloading';
+export const AUTO_UPDATE_DOWNLOADED = 'auto_update_downloaded';
+export const AUTO_UPDATE_CONFIRM = 'auto_update_confirm';
+export const ERROR = 'error';
+export const INSUFFICIENT_CREDITS = 'insufficient_credits';
+export const UPGRADE = 'upgrade';
+export const WELCOME = 'welcome';
+export const EMAIL_COLLECTION = 'email_collection';
+export const PHONE_COLLECTION = 'phone_collection';
+export const FIRST_REWARD = 'first_reward';
+export const AUTHENTICATION_FAILURE = 'auth_failure';
+export const TRANSACTION_FAILED = 'transaction_failed';
+export const REWARD_APPROVAL_REQUIRED = 'reward_approval_required';
+export const AFFIRM_PURCHASE = 'affirm_purchase';
+export const CONFIRM_CLAIM_REVOKE = 'confirm_claim_revoke';
+export const FIRST_SUBSCRIPTION = 'firstSubscription';
+export const SEND_TIP = 'send_tip';
+export const PUBLISH = 'publish';
+export const SEARCH = 'search';
+export const CONFIRM_THUMBNAIL_UPLOAD = 'confirmThumbnailUpload';
diff --git a/src/renderer/modal/modalConfirmThumbnailUpload/index.js b/src/renderer/modal/modalConfirmThumbnailUpload/index.js
new file mode 100644
index 000000000..607ea27af
--- /dev/null
+++ b/src/renderer/modal/modalConfirmThumbnailUpload/index.js
@@ -0,0 +1,18 @@
+import { connect } from 'react-redux';
+import { doCloseModal } from 'redux/actions/app';
+import { doUploadThumbnail, doUpdatePublishForm } from 'redux/actions/publish';
+import { selectPublishFormValues } from 'redux/selectors/publish';
+import ModalConfirmThumbnailUpload from './view';
+
+const select = state => {
+  const publishState = selectPublishFormValues(state);
+  return { nsfw: publishState.nsfw };
+};
+
+const perform = dispatch => ({
+  closeModal: () => dispatch(doCloseModal()),
+  upload: (path, nsfw = false) => dispatch(doUploadThumbnail(path, nsfw)),
+  updatePublishForm: value => dispatch(doUpdatePublishForm(value)),
+});
+
+export default connect(select, perform)(ModalConfirmThumbnailUpload);
diff --git a/src/renderer/modal/modalConfirmThumbnailUpload/view.jsx b/src/renderer/modal/modalConfirmThumbnailUpload/view.jsx
new file mode 100644
index 000000000..910967fe3
--- /dev/null
+++ b/src/renderer/modal/modalConfirmThumbnailUpload/view.jsx
@@ -0,0 +1,45 @@
+// @flow
+import React from 'react';
+import { Modal } from 'modal/modal';
+import { FormField } from 'component/common/form';
+
+type Props = {
+  upload: (string, boolean) => void,
+  path: string,
+  nsfw: boolean,
+  closeModal: () => void,
+  updatePublishForm: any => void,
+};
+
+class ModalConfirmThumbnailUpload extends React.PureComponent<Props> {
+  upload() {
+    this.props.upload(this.props.path, this.props.nsfw);
+    this.props.closeModal();
+  }
+
+  render() {
+    const { closeModal, path, updatePublishForm, nsfw } = this.props;
+
+    return (
+      <Modal
+        isOpen
+        contentLabel={__('Confirm Thumbnail Upload')}
+        type="confirm"
+        confirmButtonLabel={__('Upload')}
+        onConfirmed={() => this.upload()}
+        onAborted={closeModal}
+      >
+        <p>{`Confirm upload: ${path}`}</p>
+        <FormField
+          type="checkbox"
+          name="content_is_mature"
+          postfix={__('Mature audiences only')}
+          checked={nsfw}
+          onChange={event => updatePublishForm({ nsfw: event.target.checked })}
+        />
+      </Modal>
+    );
+  }
+}
+
+export default ModalConfirmThumbnailUpload;
diff --git a/src/renderer/modal/modalRouter/view.jsx b/src/renderer/modal/modalRouter/view.jsx
index 96597401f..a3046e725 100644
--- a/src/renderer/modal/modalRouter/view.jsx
+++ b/src/renderer/modal/modalRouter/view.jsx
@@ -23,8 +23,13 @@ import ModalSendTip from '../modalSendTip';
 import ModalPublish from '../modalPublish';
 import ModalSearch from '../modalSearch';
 import ModalOpenExternalLink from '../modalOpenExternalLink';
+import ModalConfirmThumbnailUpload from 'modal/modalConfirmThumbnailUpload';
 
-class ModalRouter extends React.PureComponent {
+type Props = {
+  modal: string,
+};
+
+class ModalRouter extends React.PureComponent<Props> {
   constructor(props) {
     super(props);
 
@@ -57,7 +62,7 @@ class ModalRouter extends React.PureComponent {
 
     if (
       transitionModal &&
-      (transitionModal != this.state.lastTransitionModal || page != this.state.lastTransitionPage)
+      (transitionModal !== this.state.lastTransitionModal || page !== this.state.lastTransitionPage)
     ) {
       openModal({ id: transitionModal });
       this.setState({
@@ -161,6 +166,8 @@ class ModalRouter extends React.PureComponent {
         return <ModalOpenExternalLink {...notificationProps} />;
       case MODALS.CONFIRM_TRANSACTION:
         return <ModalConfirmTransaction {...notificationProps} />;
+      case MODALS.CONFIRM_THUMBNAIL_UPLOAD:
+        return <ModalConfirmThumbnailUpload {...modalProps} />;
       default:
         return null;
     }