diff --git a/static/thumbhash.js b/static/thumbhash.js
index 2e74d83..6ba1c9a 100644
--- a/static/thumbhash.js
+++ b/static/thumbhash.js
@@ -229,8 +229,9 @@ function rgbaToDataURL(w, h, rgba) {
 function updateThumbhashImages() {
   document.querySelectorAll("[data-thumb]").forEach((entry) => {
     const hash = entry.getAttribute("data-thumb");
-
+    if (entry.getAttribute("data-thumb-decoded")) return;
     if (!hash) return;
+    entry.setAttribute("data-thumb-decoded", true);
 
     const decodedString = atob(hash);