diff --git a/src/calibre/gui2/viewer2/web_view.py b/src/calibre/gui2/viewer2/web_view.py
index cd52f74001..038db07f51 100644
--- a/src/calibre/gui2/viewer2/web_view.py
+++ b/src/calibre/gui2/viewer2/web_view.py
@@ -239,6 +239,7 @@ class WebView(RestartingWebEngineView):
 
     def __init__(self, parent=None):
         self._host_widget = None
+        self.current_cfi = None
         RestartingWebEngineView.__init__(self, parent)
         self.dead_renderer_error_shown = False
         self.render_process_failed.connect(self.render_process_died)
@@ -251,11 +252,20 @@ class WebView(RestartingWebEngineView):
         self.setPage(self._page)
         self.setAcceptDrops(False)
         self.clear()
+        self.urlChanged.connect(self.url_changed)
         if parent is not None:
             self.inspector = Inspector(parent.inspector_dock.toggleViewAction(), self)
             parent.inspector_dock.setWidget(self.inspector)
             # QTimer.singleShot(300, lambda: (parent.inspector_dock.setVisible(True), parent.inspector_dock.setMinimumWidth(650)))
 
+    def url_changed(self, url):
+        if url.hasFragment():
+            frag = url.fragment(url.FullyDecoded)
+            if frag and frag.startswith('bookpos='):
+                cfi = frag[len('bookpos='):]
+                if cfi:
+                    self.current_cfi = cfi
+
     @property
     def host_widget(self):
         ans = self._host_widget
diff --git a/src/pyj/viewer-main.pyj b/src/pyj/viewer-main.pyj
index 5dda2545f8..3a4cf247aa 100644
--- a/src/pyj/viewer-main.pyj
+++ b/src/pyj/viewer-main.pyj
@@ -18,6 +18,7 @@ from read_book.globals import runtime, ui_operations
 from read_book.iframe import main as iframe_main
 from read_book.view import View
 from session import session_defaults
+from utils import encode_query_with_path
 from viewer.constants import FAKE_HOST, FAKE_PROTOCOL
 
 
@@ -113,7 +114,12 @@ def get_mathjax_files(proceed):
 
 
 def update_url_state(replace):
-    pass  # TODO: Implement this
+    if view and view.currently_showing:
+        bookpos = view.currently_showing.bookpos
+        if bookpos:
+            query = {'bookpos': bookpos}
+            query = encode_query_with_path(query)
+            window.history.pushState(None, '', query)
 
 
 def show_error(title, msg, details):