diff --git a/static/skin/viewer.js b/static/skin/viewer.js
index 2c3c80a14..d1e7bb1ae 100644
--- a/static/skin/viewer.js
+++ b/static/skin/viewer.js
@@ -23,7 +23,7 @@ function userUrl2IframeUrl(url) {
 }
 
 function getBookFromUserUrl(url) {
-  if ( url == '' ) {
+  if ( url == '' || url.startsWith('catch/external?') ) {
     return null;
   }
 
@@ -131,6 +131,10 @@ function iframeUrl2UserUrl(url, query) {
     return '';
   }
 
+  if ( url == `${root}/catch/external` ) {
+    return `catch/external${query}`;
+  }
+
   if ( url == `${root}/search` ) {
     return `search${query}`;
   }
@@ -224,8 +228,12 @@ function handle_content_url_change() {
   const iframeContentUrl = iframeLocation.pathname;
   const iframeContentQuery = iframeLocation.search;
   const newHash = iframeUrl2UserUrl(iframeContentUrl, iframeContentQuery);
-  history.replaceState(viewerState, null, makeURL(location.search, newHash));
-  updateCurrentBookIfNeeded(newHash);
+  if ( newHash.startsWith('catch/external?') ) {
+    handleInterceptedExternalLink(newHash);
+  } else {
+    history.replaceState(viewerState, null, makeURL(location.search, newHash));
+    updateCurrentBookIfNeeded(newHash);
+  }
 };
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -262,10 +270,7 @@ function onClickEvent(e) {
   const target = matchingAncestorElement(e.target, iframeDocument, "a");
   if (target !== null && "href" in target) {
     if ( isExternalUrl(target.href) ) {
-      target.setAttribute("target", "_top");
-      if ( viewerSettings.linkBlockingEnabled ) {
-        return blockLink(target);
-      }
+      return blockLink(target);
     }
   }
 }
@@ -304,6 +309,16 @@ function setup_external_link_blocker() {
   setupEventHandler(contentIframe.contentDocument, 'a', 'click', onClickEvent);
 }
 
+function handleInterceptedExternalLink(catchExternalUrl) {
+  // The external link blocking page was loaded in the viewer iframe.
+  // We need to get rid of the viewer taskbar and display the confirmation
+  // page in the top frame.
+  const urlpath = `${root}/` + catchExternalUrl;
+  history.back(); // drop from the browsing history the state where the
+                  // external link catcher page is loaded in the iframe ...
+  window.location = urlpath; // ... and load it in the top frame instead
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // End of external link blocking
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/test/server.cpp b/test/server.cpp
index 961ef9a06..862dd3ba5 100644
--- a/test/server.cpp
+++ b/test/server.cpp
@@ -73,7 +73,7 @@ const ResourceCollection resources200Compressible{
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/taskbar.css" },
   { STATIC_CONTENT,  "/ROOT%23%3F/skin/taskbar.css?cacheid=bbdaf425" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/viewer.js" },
-  { STATIC_CONTENT,  "/ROOT%23%3F/skin/viewer.js?cacheid=b9a574d4" },
+  { STATIC_CONTENT,  "/ROOT%23%3F/skin/viewer.js?cacheid=202f8641" },
   { 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" },
@@ -312,7 +312,7 @@ R"EXPECTEDRESULT(    <link type="text/css" href="./skin/taskbar.css?cacheid=bbda
     <link type="text/css" href="./skin/css/autoComplete.css?cacheid=08951e06" rel="Stylesheet" />
     <script type="module" src="./skin/i18n.js?cacheid=2cf0f8c5" defer></script>
     <script type="text/javascript" src="./skin/languages.js?cacheid=b00b12db" defer></script>
-    <script type="text/javascript" src="./skin/viewer.js?cacheid=b9a574d4" defer></script>
+    <script type="text/javascript" src="./skin/viewer.js?cacheid=202f8641" defer></script>
     <script type="text/javascript" src="./skin/autoComplete.min.js?cacheid=1191aaaf"></script>
       const blankPageUrl = root + "/skin/blank.html?cacheid=6b1fa032";
             <img src="./skin/langSelector.svg?cacheid=00b59961">