diff --git a/pandora/document/views.py b/pandora/document/views.py
index 6657f92cc..8ce0f35b5 100644
--- a/pandora/document/views.py
+++ b/pandora/document/views.py
@@ -1,8 +1,9 @@
 # -*- coding: utf-8 -*-
 
+from glob import glob
+import mimetypes
 import os
 import re
-from glob import glob
 import unicodedata
 
 import ox
@@ -379,11 +380,13 @@ actions.register(sortDocuments, cache=False)
 def file(request, id, name=None):
     document = get_document_or_404_json(request, id)
     accept = request.headers.get("Accept")
+    mime_type = mimetypes.guess_type(document.file.path)[0]
+    mime_type = 'image/%s' % document.extension
     if accept and 'image/' in accept and document.extension in (
-        'webp', 'heif', 'heic', 'avif'
-    ) and document.extension not in accept:
+        'webp', 'heif', 'heic', 'avif', 'tiff'
+    ) and mime_type not in accept:
         image_size = max(document.width, document.height)
-        return HttpFileResponse(document.thumbnail(image_size))
+        return HttpFileResponse(document.thumbnail(image_size, accept=accept))
     return HttpFileResponse(document.file.path)
 
 def thumbnail(request, id, size=256, page=None):
diff --git a/static/js/uploadDocumentDialog.js b/static/js/uploadDocumentDialog.js
index 50eaeb0a4..7b80a241e 100644
--- a/static/js/uploadDocumentDialog.js
+++ b/static/js/uploadDocumentDialog.js
@@ -8,8 +8,6 @@ pandora.ui.uploadDocumentDialog = function(options, callback) {
         existingFiles = [],
         uploadFiles = [],
 
-        supportedExtensions = ['gif', 'jpg', 'jpeg', 'pdf', 'png', 'webp', 'heic', 'heif', 'avif'],
-
         filename,
 
         ids = [],
@@ -72,7 +70,7 @@ pandora.ui.uploadDocumentDialog = function(options, callback) {
             });
 
     if (!Ox.every(extensions, function(extension) {
-        return Ox.contains(supportedExtensions, extension)
+        return Ox.contains(pandora.documentExtensions, extension)
     })) {
         return errorDialog(
             Ox._('Supported file types are GIF, JPG, PNG and PDF.')
diff --git a/static/js/utils.js b/static/js/utils.js
index 29e0d75c3..ea28e18fa 100644
--- a/static/js/utils.js
+++ b/static/js/utils.js
@@ -420,13 +420,28 @@ pandora.createLinks = function($element) {
     });
 };
 
+pandora.imageExtensions = [
+    'avif',
+    'gif',
+    'heic',
+    'heif',
+    'jpeg',
+    'jpg',
+    'png',
+    'tiff',
+    'webp'
+];
+
+pandora.documentExtensions = [
+    'pdf', /* 'epub', 'txt', */
+].concat(pandora.imageExtensions);
+
 pandora.uploadDroppedFiles = function(files) {
-    var documentExtensions = ['pdf', /* 'epub', 'txt', */ 'png', 'gif', 'jpg', 'jpeg', 'webp', 'heic', 'heif', 'avif'];
     files = Ox.map(files, function(file) { return file });
 
     if (files.every(function(file) {
         var extension = file.name.split('.').pop().toLowerCase()
-        return Ox.contains(documentExtensions, extension)
+        return Ox.contains(pandora.documentExtensions, extension)
     })) {
         pandora.ui.uploadDocumentDialog({
             files: files
@@ -2132,9 +2147,7 @@ pandora.getSpan = function(state, val, callback) {
                     } else {
                         state.span = val;
                     }
-                } else if (Ox.contains([
-                    'gif', 'gif', 'jpg', 'png', 'webp', 'heic', 'heif', 'avif'
-                ], extension)) {
+                } else if (Ox.contains(pandora.imageExtensions, extension)) {
                     values = val.split(',');
                     if (values.length == 4) {
                         state.span = values.map(function(number, index) {