diff --git a/script/single.js b/script/single.js
index 479b433..31e464b 100644
--- a/script/single.js
+++ b/script/single.js
@@ -28,7 +28,9 @@ function setImage(id, src, width, height, href, cw, firstLoad) {
   let caption = document.getElementById('cw');
   let newCaption;
 
-  if (!skipAll.checked && !opened.has(id) && cw) {
+  let checked = skipAll ? skipAll.checked : false;
+
+  if (!checked && !opened.has(id) && cw) {
     newCaption = document.getElementById('cw-template')
                     .content.firstElementChild.cloneNode(true);
     newCaption.querySelector('#cw-text').innerHTML = cw;
@@ -96,10 +98,12 @@ function setup() {
     button.onchange = e => { if (button.checked) activateButton(button); };
   }
 
-  skipAll.onchange = e => { if (skipAll.checked) {
-    let caption = document.getElementById('cw');
-    if (caption) { openCW(null, caption, false); }
-  } };
+  if (skipAll) {
+    skipAll.onchange = e => { if (skipAll.checked) {
+      let caption = document.getElementById('cw');
+      if (caption) { openCW(null, caption, false); }
+    } };
+  }
 
   window.addEventListener('popstate', useFragment);
   useFragment(true);