diff --git a/src/book.js b/src/book.js
index d597049..15a7be3 100644
--- a/src/book.js
+++ b/src/book.js
@@ -297,7 +297,6 @@ export class Book {
    */
   async createoutputfiles(isPreview) {
     const previewFrame = document.getElementById('pdf');
-    previewFrame.style.display = 'none';
     let previewPdf = null;
 
     //  create a directory named after the input pdf and fill it with
@@ -372,25 +371,25 @@ export class Book {
           for (const sig of signatures) {
             // Adding pages to aggregate PDFs has to be done in order, not with promises
             if (aggregate.front) {
-              const copiedPages = await aggregate.front.copyPages(
+              const copiedPages = await aggregate.front.embedPdf(
                 sig.front,
                 sig.front.getPageIndices()
               );
-              copiedPages.forEach((page) => aggregate.front.addPage(page));
+              copiedPages.forEach((page) => aggregate.front.addPage().drawPage(page));
             }
             if (aggregate.back) {
-              const copiedPages = await aggregate.back.copyPages(
+              const copiedPages = await aggregate.back.embedPdf(
                 sig.back,
                 sig.back.getPageIndices()
               );
-              copiedPages.forEach((page) => aggregate.back.addPage(page));
+              copiedPages.forEach((page) => aggregate.back.addPage().drawPage(page));
             }
             if (aggregate.duplex) {
-              const copiedPages = await aggregate.duplex.copyPages(
+              const copiedPages = await aggregate.duplex.embedPdf(
                 sig.duplex,
                 sig.duplex.getPageIndices()
               );
-              copiedPages.forEach((page) => aggregate.duplex.addPage(page));
+              copiedPages.forEach((page) => aggregate.duplex.addPage().drawPage(page));
             }
           }
           if (aggregate.front) {
@@ -443,11 +442,11 @@ export class Book {
       viewerPrefs.setCenterWindow(true);
       viewerPrefs.setDisplayDocTitle(true);
 
+      previewFrame.src = pdfDataUri;
       previewFrame.style.width = `450px`;
       const height = (this.papersize[1] / this.papersize[0]) * 500;
       previewFrame.style.height = `${height}px`;
       previewFrame.style.display = '';
-      previewFrame.src = pdfDataUri;
     }
 
     if (!isPreview) return this.saveZip();
diff --git a/src/utils/changeHandlers.js b/src/utils/changeHandlers.js
index 8c774a4..536ac14 100644
--- a/src/utils/changeHandlers.js
+++ b/src/utils/changeHandlers.js
@@ -3,7 +3,11 @@
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 import { saveForm, updateRenderedForm } from './formUtils';
-import { updatePaperSelectOptionsUnits, updateAddOrRemoveCustomPaperOption } from './renderUtils';
+import {
+  updatePaperSelectOptionsUnits,
+  updateAddOrRemoveCustomPaperOption,
+  clearPreview,
+} from './renderUtils';
 
 export function handleInputChange(book, bookbinderForm) {
   const formData = new FormData(bookbinderForm);
@@ -17,6 +21,7 @@ export function handleInputChange(book, bookbinderForm) {
 }
 
 export function handleFileChange(e, book) {
+  clearPreview();
   const fileList = e.target.files;
   if (fileList.length > 0) {
     const updated = book.openpdf(fileList[0]);
diff --git a/src/utils/clickHandlers.js b/src/utils/clickHandlers.js
index 9964798..6c6e3a0 100644
--- a/src/utils/clickHandlers.js
+++ b/src/utils/clickHandlers.js
@@ -3,7 +3,11 @@
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 import { resetForm } from './formUtils';
-import { updateAddOrRemoveCustomPaperOption, updatePaperSelectOptionsUnits } from './renderUtils';
+import {
+  clearPreview,
+  updateAddOrRemoveCustomPaperOption,
+  updatePaperSelectOptionsUnits,
+} from './renderUtils';
 
 export function handleGenerateClick(generateEl, book) {
   generateEl.setAttribute('disabled', true);
@@ -28,6 +32,7 @@ export function handleGenerateClick(generateEl, book) {
 export function handlePreviewClick(previewEl, book) {
   previewEl.setAttribute('disabled', true);
   previewEl.innerText = 'Generating Preview...';
+  clearPreview();
   const result = book.createoutputfiles(true);
   result
     .then(() => {
diff --git a/src/utils/pdf.js b/src/utils/pdf.js
index 7bc264f..f4c2eba 100644
--- a/src/utils/pdf.js
+++ b/src/utils/pdf.js
@@ -13,16 +13,16 @@ export async function interleavePages(pdfA, pdfB) {
   const pageCount = Math.max(pdfA.getPageCount(), pdfB.getPageCount());
   const promises = [];
 
-  for (let i = 0; i < pageCount; i++) {
-    const pageAPromise = pdfA.getPage(i);
-    const pageBPromise = pdfB.getPage(i);
+  const pagesAPromise = mergedPdf.copyPages(pdfA, pdfA.getPageIndices());
+  const pagesBPromise = mergedPdf.copyPages(pdfB, pdfB.getPageIndices());
 
-    promises.push(pageAPromise, pageBPromise);
+  promises.push(pagesAPromise, pagesBPromise);
 
-    const [pageA, pageB] = await Promise.all([pageAPromise, pageBPromise]);
+  const [pagesA, pagesB] = await Promise.all([pagesAPromise, pagesBPromise]);
 
-    if (pageA) mergedPdf.addPage((await mergedPdf.copyPages(pdfA, [i]))[0]);
-    if (pageB) mergedPdf.addPage((await mergedPdf.copyPages(pdfB, [i]))[0]);
+  for (let i = 0; i < pageCount; i++) {
+    if (i < pagesA.length) mergedPdf.addPage(pagesA[i]);
+    if (i < pagesB.length) mergedPdf.addPage(pagesB[i]);
   }
 
   await Promise.all(promises); // Wait for all page retrieval promises to resolve
diff --git a/src/utils/renderUtils.js b/src/utils/renderUtils.js
index 54c2e6a..b627be1 100644
--- a/src/utils/renderUtils.js
+++ b/src/utils/renderUtils.js
@@ -251,3 +251,9 @@ export function renderFormFromSettings(configuration) {
     example.style.display = example.id === selectedValue ? 'block' : 'none';
   });
 }
+
+export function clearPreview() {
+  const previewFrame = document.getElementById('pdf');
+  previewFrame.style.display = 'none';
+  previewFrame.src = '';
+}