diff --git a/src/calibre/gui2/preferences/__init__.py b/src/calibre/gui2/preferences/__init__.py
index 3169cafffa..ffffed091d 100644
--- a/src/calibre/gui2/preferences/__init__.py
+++ b/src/calibre/gui2/preferences/__init__.py
@@ -8,7 +8,7 @@ __docformat__ = 'restructuredtext en'
 import textwrap
 
 from PyQt5.Qt import (QWidget, pyqtSignal, QCheckBox, QAbstractSpinBox,
-    QLineEdit, QComboBox, Qt, QIcon, QDialog, QVBoxLayout, QRadioButton,
+    QLineEdit, QComboBox, Qt, QIcon, QDialog, QVBoxLayout,
     QDialogButtonBox)
 
 from calibre.customize.ui import preferences_plugins
@@ -101,9 +101,6 @@ class Setting(object):
         if isinstance(self.gui_obj, QCheckBox):
             self.datatype = 'bool'
             self.gui_obj.stateChanged.connect(self.changed)
-        elif isinstance(self.gui_obj, QRadioButton):
-            self.datatype = 'bool'
-            self.gui_obj.toggled.connect(self.changed)
         elif isinstance(self.gui_obj, QAbstractSpinBox):
             self.datatype = 'number'
             self.gui_obj.valueChanged.connect(self.changed)
@@ -115,7 +112,7 @@ class Setting(object):
             self.gui_obj.editTextChanged.connect(self.changed)
             self.gui_obj.currentIndexChanged.connect(self.changed)
         else:
-            raise ValueError('Unknown data type')
+            raise ValueError('Unknown data type %s' % self.gui_obj.__class__)
 
         if isinstance(self.config_obj, ConfigProxy) and \
                 not unicode(self.gui_obj.toolTip()):
diff --git a/src/calibre/gui2/preferences/search.py b/src/calibre/gui2/preferences/search.py
index 2cff7a9fca..b0750d8049 100644
--- a/src/calibre/gui2/preferences/search.py
+++ b/src/calibre/gui2/preferences/search.py
@@ -7,11 +7,13 @@ __docformat__ = 'restructuredtext en'
 
 from PyQt5.Qt import QApplication
 
-from calibre.gui2.preferences import ConfigWidgetBase, test_widget, CommaSeparatedList
+from calibre.gui2.preferences import ConfigWidgetBase, test_widget, \
+        CommaSeparatedList, AbortCommit
 from calibre.gui2.preferences.search_ui import Ui_Form
 from calibre.gui2 import config, error_dialog, gprefs
 from calibre.utils.config import prefs
 from calibre.utils.icu import sort_key
+from calibre.library.caches import set_use_primary_find_in_search
 
 class ConfigWidget(ConfigWidgetBase, Ui_Form):
 
@@ -210,6 +212,11 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         self.gst_value.blockSignals(False)
 
     def commit(self):
+        if self.opt_case_sensitive.isChecked() and self.opt_use_primary_find_in_search.isChecked():
+            error_dialog(self, _('Incompatible options'), _(
+                'The option to have un-accented characters match accented characters has no effect'
+                ' if you also turn on case-sensitive searching. So only turn on one of those options'), show=True)
+            raise AbortCommit()
         if self.gst_changed:
             self.db.new_api.set_pref('grouped_search_terms', self.gst)
             self.db.field_metadata.add_grouped_search_terms(self.gst)
@@ -224,7 +231,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         return ConfigWidgetBase.commit(self)
 
     def refresh_gui(self, gui):
-        gui.current_db.new_api.clear_caches()  # Clear the search cache
+        set_use_primary_find_in_search(prefs['use_primary_find_in_search'])
         gui.set_highlight_only_button_icon()
         if self.muc_changed:
             gui.tags_view.recount()
diff --git a/src/calibre/gui2/preferences/search.ui b/src/calibre/gui2/preferences/search.ui
index 69a5e3029e..c00612777a 100644
--- a/src/calibre/gui2/preferences/search.ui
+++ b/src/calibre/gui2/preferences/search.ui
@@ -307,14 +307,14 @@ to be shown as user categories</string>
     </widget>
    </item>
    <item row="3" column="0">
-    <widget class="QRadioButton" name="opt_case_sensitive">
+    <widget class="QCheckBox" name="opt_case_sensitive">
      <property name="text">
       <string>Case sensitive searching</string>
      </property>
     </widget>
    </item>
    <item row="3" column="1">
-    <widget class="QRadioButton" name="opt_use_primary_find_in_search">
+    <widget class="QCheckBox" name="opt_use_primary_find_in_search">
      <property name="text">
       <string>Unaccented characters match accented characters</string>
      </property>
diff --git a/src/calibre/utils/config_base.py b/src/calibre/utils/config_base.py
index 8baf932b94..bfc8d7b92f 100644
--- a/src/calibre/utils/config_base.py
+++ b/src/calibre/utils/config_base.py
@@ -440,8 +440,7 @@ def create_global_prefs(conf_obj=None):
                    'libraries. Note that this option will have no effect if you turn '
                    'on case-sensitive searching')%u'\xf1')
     c.add_opt('case_sensitive', default=False, help=_(
-        'Make searches case-sensitive. Note that turning on case-sensitive searches disables matching of '
-        'accented characters by their unaccented versions.'))
+        'Make searches case-sensitive'))
 
     c.add_opt('migrated', default=False, help='For Internal use. Don\'t modify.')
     return c