diff --git a/static/skin/viewer.js b/static/skin/viewer.js
index 99ee06c4..75be6dc1 100644
--- a/static/skin/viewer.js
+++ b/static/skin/viewer.js
@@ -352,6 +352,10 @@ function linkShouldBeOpenedInANewWindow(linkElement, mouseEvent) {
       || mouseEvent.metaKey /* on Macs */;
 }
 
+function goingToOpenALinkToAnUndisplayableResource(url) {
+  return !navigator.pdfViewerEnabled && url.pathname.endsWith('.pdf');
+}
+
 function onClickEvent(e) {
   const iframeDocument = contentIframe.contentDocument;
   const target = matchingAncestorElement(e.target, iframeDocument, "a");
@@ -359,7 +363,8 @@ function onClickEvent(e) {
     const target_href = getRealHref(target);
     const target_url = new URL(target_href, iframeDocument.location);
     const isExternalAppUrl = urlMustBeHandledByAnExternalApp(target_url);
-    if ( isExternalAppUrl && !viewerSettings.linkBlockingEnabled ) {
+    if ( (isExternalAppUrl && !viewerSettings.linkBlockingEnabled)
+         || goingToOpenALinkToAnUndisplayableResource(target_url) ) {
         target.setAttribute("target", "_blank");
     }
 
diff --git a/test/server.cpp b/test/server.cpp
index 8f0b1a3d..f00bb691 100644
--- a/test/server.cpp
+++ b/test/server.cpp
@@ -75,7 +75,7 @@ const ResourceCollection resources200Compressible{
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/taskbar.css" },
   { STATIC_CONTENT,  "/ROOT%23%3F/skin/taskbar.css?cacheid=80d56607" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/viewer.js" },
-  { STATIC_CONTENT,  "/ROOT%23%3F/skin/viewer.js?cacheid=fdec37a7" },
+  { STATIC_CONTENT,  "/ROOT%23%3F/skin/viewer.js?cacheid=787e61d4" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/fonts/Poppins.ttf" },
   { STATIC_CONTENT,  "/ROOT%23%3F/skin/fonts/Poppins.ttf?cacheid=af705837" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/fonts/Roboto.ttf" },
@@ -327,7 +327,7 @@ R"EXPECTEDRESULT(    <link type="text/css" href="./skin/kiwix.css?cacheid=2158fa
     <script type="text/javascript" src="./skin/polyfills.js?cacheid=a0e0343d"></script>
     <script type="module" src="./skin/i18n.js?cacheid=071abc9a" defer></script>
     <script type="text/javascript" src="./skin/languages.js?cacheid=ee7d95b5" defer></script>
-    <script type="text/javascript" src="./skin/viewer.js?cacheid=fdec37a7" defer></script>
+    <script type="text/javascript" src="./skin/viewer.js?cacheid=787e61d4" defer></script>
     <script type="text/javascript" src="./skin/autoComplete/autoComplete.min.js?cacheid=1191aaaf"></script>
       const blankPageUrl = root + "/skin/blank.html?cacheid=6b1fa032";
           <label for="kiwix_button_show_toggle"><img src="./skin/caret.png?cacheid=22b942b4" alt=""></label>