diff --git a/package.json b/package.json
index 67366cc9de7961d1bc0acfacd7d6ededd6a1b544..5f4707502d28761f2bed565368eb42a83d639ac2 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,7 @@
     "jszip": "^3.5.0",
     "lit-element": "^2.3.1",
     "lit-html": "^1.2.1",
-    "pdfjs-dist": "^2.4.456",
+    "pdfjs-dist": "2.6.347",
     "universal-router": "^9.0.1",
     "webdav": "^3.3.0"
   },
diff --git a/rollup.config.js b/rollup.config.js
index a2bdf4c7001a5423c0f9284d955b89338fe79539..c4282832db7f65ef1e6aa6ede3baf3013b88d28f 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -73,6 +73,9 @@ httpbin.org ${getOrigin(config.nextcloudBaseURL)} www.handy-signatur.at \
 ${getOrigin(config.pdfAsQualifiedlySigningServer)}; \
 img-src * blob: data:`;
 
+function replaceAll(string, search, replace) {
+    return string.split(search).join(replace);
+}
 
 export default (async () => {
     let privatePath = await getDistPath(pkg.name)
@@ -190,7 +193,7 @@ Dependencies:
                     src: await getPackagePath('pdfjs-dist', 'es5/build/pdf.worker.js'),
                     dest: 'dist/' + await getDistPath(pkg.name, 'pdfjs'),
                     // enable signatures in pdf preview
-                    transform: (contents) => contents.toString().replace('"Sig"', '"Sig-patched-show-anyway"')
+                    transform: (contents) => replaceAll(contents.toString(), '"Sig"', '"Sig-patched-show-anyway"')
                 },
                 {src: await getPackagePath('pdfjs-dist', 'cmaps/*'), dest: 'dist/' + await getDistPath(pkg.name, 'pdfjs')}, // do we want all map files?
                 {src: await getPackagePath('@dbp-toolkit/font-source-sans-pro', 'files/*'), dest: 'dist/' + await getDistPath(pkg.name, 'fonts/source-sans-pro')},