diff --git a/photologue_custom/templates/photologue/upload.html b/photologue_custom/templates/photologue/upload.html
index ec64b72..e4a5c6d 100644
--- a/photologue_custom/templates/photologue/upload.html
+++ b/photologue_custom/templates/photologue/upload.html
@@ -28,6 +28,7 @@ SPDX-License-Identifier: GPL-3.0-or-later
 
 {% block extrajs %}
 <script>
+// When user drags files, register them in the file field
 const dropZone = document.getElementById('drop-zone');
 const uploadInput = document.getElementById('id_file_field');
 
@@ -47,6 +48,18 @@ dropZone.ondragleave = function() {
     this.className = 'upload-drop-zone';
     return false;
 }
+
+// When user selects an existing gallery, disable new gallery fields
+const gallerySelect = document.getElementById('id_gallery')
+gallerySelectUpdate = () => {
+    const useGallery = (gallerySelect.value !== "");
+    document.getElementById('id_new_gallery_title').disabled = useGallery;
+    document.getElementById('id_new_gallery_date_start').disabled = useGallery;
+    document.getElementById('id_new_gallery_date_end').disabled = useGallery;
+    document.getElementById('id_new_gallery_tags').disabled = useGallery;
+}
+gallerySelect.addEventListener('change', gallerySelectUpdate);
+gallerySelectUpdate();
 </script>
 {% endblock %}