diff --git a/app/renderer/js/pages/preference/new-server-form.js b/app/renderer/js/pages/preference/new-server-form.js
index 4f5a9ea1..60c6cb37 100644
--- a/app/renderer/js/pages/preference/new-server-form.js
+++ b/app/renderer/js/pages/preference/new-server-form.js
@@ -43,11 +43,13 @@ class NewServerForm extends BaseComponent {
 	}
 
 	submitFormHandler() {
+		this.$saveServerButton.children[1].innerHTML = 'Adding...';
 		DomainUtil.checkDomain(this.$newServerUrl.value).then(serverConf => {
 			DomainUtil.addDomain(serverConf).then(() => {
 				this.props.onChange(this.props.index);
 			});
 		}, errorMessage => {
+			this.$saveServerButton.children[1].innerHTML = 'Add';
 			alert(errorMessage);
 		});
 	}
diff --git a/app/renderer/js/utils/domain-util.js b/app/renderer/js/utils/domain-util.js
index 1a5a6851..db5a27a4 100644
--- a/app/renderer/js/utils/domain-util.js
+++ b/app/renderer/js/utils/domain-util.js
@@ -99,8 +99,7 @@ class DomainUtil {
 	checkDomain(domain, silent = false) {
 		if (!silent && this.duplicateDomain(domain)) {
 			// Do not check duplicate in silent mode
-			alert('This server has been added.');
-			return;
+			return Promise.reject('This server has been added.');
 		}
 
 		domain = this.formatUrl(domain);