diff --git a/ghost/admin/app/components/modals/upload-theme.js b/ghost/admin/app/components/modals/upload-theme.js
index 8e606c1652..1c162b1e89 100644
--- a/ghost/admin/app/components/modals/upload-theme.js
+++ b/ghost/admin/app/components/modals/upload-theme.js
@@ -12,7 +12,7 @@ import injectService from 'ember-service/inject';
 
 export default ModalComponent.extend({
 
-    accept: 'application/zip',
+    accept: ['application/zip', 'application/x-zip-compressed'],
     availableThemes: null,
     closeDisabled: false,
     file: null,
diff --git a/ghost/admin/app/controllers/settings/labs.js b/ghost/admin/app/controllers/settings/labs.js
index 5bd259a4e3..597c86d6c4 100644
--- a/ghost/admin/app/controllers/settings/labs.js
+++ b/ghost/admin/app/controllers/settings/labs.js
@@ -11,7 +11,7 @@ export default Controller.extend({
     submitting: false,
     showDeleteAllModal: false,
 
-    importMimeType: ['application/json', 'application/zip'],
+    importMimeType: ['application/json', 'application/zip', 'application/x-zip-compressed'],
 
     ghostPaths: injectService(),
     notifications: injectService(),