diff --git a/src/calibre/gui2/viewer/main.py b/src/calibre/gui2/viewer/main.py
index 96cf73a1db..a998ecf353 100644
--- a/src/calibre/gui2/viewer/main.py
+++ b/src/calibre/gui2/viewer/main.py
@@ -15,8 +15,7 @@ from calibre.gui2.viewer.toc import TOC
 from calibre.gui2.widgets import ProgressIndicator
 from calibre.gui2 import (
     Application, ORG_NAME, APP_UID, choose_files, info_dialog, error_dialog,
-    open_url, setup_gui_option_parser, detach_gui,
-    workaround_broken_under_mouse)
+    open_url, setup_gui_option_parser, detach_gui)
 from calibre.ebooks.oeb.iterator.book import EbookIterator
 from calibre.ebooks import DRMError
 from calibre.constants import islinux, filesystem_encoding
@@ -156,12 +155,6 @@ class EbookViewer(MainWindow):
         self.action_toggle_paged_mode.toggled[bool].connect(self.toggle_paged_mode)
         if (start_in_fullscreen or self.view.document.start_in_fullscreen):
             self.action_full_screen.trigger()
-        if workaround_broken_under_mouse is not None:
-            for bar in (self.tool_bar, self.tool_bar2):
-                for ac in bar.actions():
-                    m = ac.menu()
-                    if m is not None:
-                        m.aboutToHide.connect(partial(workaround_broken_under_mouse, bar.widgetForAction(ac)))
 
     def toggle_paged_mode(self, checked, at_start=False):
         in_paged_mode = not self.action_toggle_paged_mode.isChecked()
diff --git a/src/calibre/gui2/viewer/ui.py b/src/calibre/gui2/viewer/ui.py
index 8010bf61d2..311484634d 100644
--- a/src/calibre/gui2/viewer/ui.py
+++ b/src/calibre/gui2/viewer/ui.py
@@ -7,15 +7,15 @@ __license__ = 'GPL v3'
 __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import textwrap
+from functools import partial
 
-from PyQt4.Qt import (
+from PyQt5.Qt import (
     QIcon, QWidget, Qt, QGridLayout, QScrollBar, QToolBar, QAction,
     QToolButton, QMenu, QDoubleSpinBox, pyqtSignal, QLineEdit,
     QRegExpValidator, QRegExp, QPalette, QColor, QBrush, QPainter,
-    QDockWidget, QSize, QLabel)
-from PyQt4.QtWebKit import QWebView
+    QDockWidget, QSize, QWebView, QLabel)
 
-from calibre.gui2 import rating_font
+from calibre.gui2 import rating_font, workaround_broken_under_mouse
 from calibre.gui2.main_window import MainWindow
 from calibre.gui2.search_box import SearchBox2
 from calibre.gui2.viewer.documentview import DocumentView
@@ -278,6 +278,13 @@ class Main(MainWindow):
 
         self.resize(653, 746)
 
+        if workaround_broken_under_mouse is not None:
+            for bar in (self.tool_bar, self.tool_bar2):
+                for ac in bar.actions():
+                    m = ac.menu()
+                    if m is not None:
+                        m.aboutToHide.connect(partial(workaround_broken_under_mouse, bar.widgetForAction(ac)))
+
     def resizeEvent(self, ev):
         if self.metadata.isVisible():
             self.metadata.update_layout()