diff --git a/src/calibre/gui2/preferences/__init__.py b/src/calibre/gui2/preferences/__init__.py
index 7267716ea8..54eb2f713c 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 PyQt4.Qt import QWidget, pyqtSignal, QCheckBox, QAbstractSpinBox, \
-    QLineEdit, QComboBox, QVariant
+    QLineEdit, QComboBox, QVariant, Qt
 
 from calibre.customize.ui import preferences_plugins
 from calibre.utils.config import ConfigProxy
@@ -82,6 +82,8 @@ class ConfigWidgetInterface(object):
 
 class Setting(object):
 
+    CHOICES_SEARCH_FLAGS = Qt.MatchExactly | Qt.MatchCaseSensitive
+
     def __init__(self, name, config_obj, widget, gui_name=None,
             empty_string_is_None=True, choices=None, restart_required=False):
         self.name, self.gui_name = name, gui_name
@@ -168,7 +170,8 @@ class Setting(object):
         elif self.datatype == 'string':
             self.gui_obj.setText(val if val else '')
         elif self.datatype == 'choice':
-            idx = self.gui_obj.findData(QVariant(val))
+            idx = self.gui_obj.findData(QVariant(val), role=Qt.UserRole,
+                    flags=self.CHOICES_SEARCH_FLAGS)
             if idx == -1:
                 idx = 0
             self.gui_obj.setCurrentIndex(idx)
diff --git a/src/calibre/gui2/preferences/behavior.py b/src/calibre/gui2/preferences/behavior.py
index aeee6e5064..45a63ce529 100644
--- a/src/calibre/gui2/preferences/behavior.py
+++ b/src/calibre/gui2/preferences/behavior.py
@@ -9,7 +9,7 @@ import re
 
 from PyQt4.Qt import Qt, QVariant, QListWidgetItem
 
-from calibre.gui2.preferences import ConfigWidgetBase, test_widget
+from calibre.gui2.preferences import ConfigWidgetBase, test_widget, Setting
 from calibre.gui2.preferences.behavior_ui import Ui_Form
 from calibre.gui2 import config, info_dialog, dynamic
 from calibre.utils.config import prefs
@@ -20,6 +20,10 @@ from calibre.ebooks.oeb.iterator import is_supported
 from calibre.constants import iswindows
 from calibre.utils.icu import sort_key
 
+class OutputFormatSetting(Setting):
+
+    CHOICES_SEARCH_FLAGS = Qt.MatchFixedString
+
 class ConfigWidget(ConfigWidgetBase, Ui_Form):
 
     def genesis(self, gui):
@@ -43,7 +47,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         output_formats = list(sorted(available_output_formats()))
         output_formats.remove('oeb')
         choices = [(x.upper(), x) for x in output_formats]
-        r('output_format', prefs, choices=choices)
+        r('output_format', prefs, choices=choices, setting=OutputFormatSetting)
 
         restrictions = sorted(saved_searches().names(), key=sort_key)
         choices = [('', '')] + [(x, x) for x in restrictions]