diff --git a/src/calibre/gui2/viewer/toolbars.py b/src/calibre/gui2/viewer/toolbars.py
index 27de1c8434..597008341a 100644
--- a/src/calibre/gui2/viewer/toolbars.py
+++ b/src/calibre/gui2/viewer/toolbars.py
@@ -50,6 +50,7 @@ def all_actions():
             'previous': Action('previous.png', _('Previous page'), 'previous'),
             'toc': Action('toc.png', _('Table of Contents'), 'toggle_toc'),
             'bookmarks': Action('bookmarks.png', _('Bookmarks'), 'toggle_bookmarks'),
+            'inspector': Action('debug.png', _('Inspector'), 'toggle_inspector'),
             'reference': Action('reference.png', _('Toggle Reference mode'), 'toggle_reference_mode'),
             'lookup': Action('generic-library.png', _('Lookup words'), 'toggle_lookup'),
             'chrome': Action('tweaks.png', _('Show viewer controls'), 'show_chrome'),
@@ -64,7 +65,7 @@ def all_actions():
 DEFAULT_ACTIONS = (
         'back', 'forward', None, 'open', 'copy', 'increase_font_size', 'decrease_font_size', 'fullscreen',
         None, 'previous', 'next', None, 'toc', 'bookmarks', 'lookup', 'reference', 'chrome', None, 'mode', 'print', 'preferences',
-        'metadata'
+        'metadata', 'inspector'
 )
 
 
@@ -155,6 +156,8 @@ class ActionsToolBar(ToolBar):
         a.setCheckable(True)
         self.lookup_action = a = shortcut_action('lookup')
         a.setCheckable(True)
+        self.inspector_action = a = shortcut_action('inspector')
+        a.setCheckable(True)
         self.chrome_action = shortcut_action('chrome')
 
         self.mode_action = a = shortcut_action('mode')
@@ -191,7 +194,7 @@ class ActionsToolBar(ToolBar):
         self.reference_action.setChecked(enabled)
 
     def update_dock_actions(self, visibility_map):
-        for k in ('toc', 'bookmarks', 'lookup'):
+        for k in ('toc', 'bookmarks', 'lookup', 'inspector'):
             ac = getattr(self, '{}_action'.format(k))
             ac.setChecked(visibility_map[k])