diff --git a/src/BookReader/Mode2UpLit.js b/src/BookReader/Mode2UpLit.js
index f2a8bfdfd..6ce856e89 100644
--- a/src/BookReader/Mode2UpLit.js
+++ b/src/BookReader/Mode2UpLit.js
@@ -785,4 +785,4 @@ export class LeafEdges extends LitElement {
   mouseEventToPageIndex(e) {
     return Math.floor(this.leftIndex + (e.offsetX / this.offsetWidth) * (this.rightIndex - this.leftIndex + 1));
   }
-}
+}
\ No newline at end of file
diff --git a/src/BookReader/ModeThumb.js b/src/BookReader/ModeThumb.js
index 763c89378..82b8934a9 100644
--- a/src/BookReader/ModeThumb.js
+++ b/src/BookReader/ModeThumb.js
@@ -329,7 +329,7 @@ export class ModeThumb extends ModeAbstract {
         leafIndex = 0;
       }
 
-      const leafHeight = floor((book.getPageHeight(leafIndex) * this.br.thumbWidth) / book.getPageWidth(leafIndex));
+      const leafHeight = floor((book.getPageHeight(i) * this.br.thumbWidth) / book.getPageWidth(i));
       if (leafHeight > rowHeight) { rowHeight = leafHeight; }
       if (leafIndex == 0) {
         leafTop = bottomPos;