diff --git a/src/calibre/gui2/tweak_book/diff/highlight.py b/src/calibre/gui2/tweak_book/diff/highlight.py
index cf9524788a..eeac053fb8 100644
--- a/src/calibre/gui2/tweak_book/diff/highlight.py
+++ b/src/calibre/gui2/tweak_book/diff/highlight.py
@@ -12,13 +12,7 @@ from PyQt4.Qt import QTextDocument, QTextCursor, QTextCharFormat, QPlainTextDocu
 
 from calibre.gui2.tweak_book import tprefs
 from calibre.gui2.tweak_book.editor.text import get_highlighter as calibre_highlighter, SyntaxHighlighter
-from calibre.gui2.tweak_book.editor.themes import THEMES, default_theme, highlight_to_char_format
-
-def get_theme():
-    theme = THEMES.get(tprefs['editor_theme'], None)
-    if theme is None:
-        theme = THEMES[default_theme()]
-    return theme
+from calibre.gui2.tweak_book.editor.themes import get_theme, highlight_to_char_format
 
 NULL_FMT = QTextCharFormat()
 
@@ -29,7 +23,7 @@ class QtHighlighter(QTextDocument):
         self.l = QPlainTextDocumentLayout(self)
         self.setDocumentLayout(self.l)
         self.highlighter = hlclass()
-        self.highlighter.apply_theme(get_theme())
+        self.highlighter.apply_theme(get_theme(tprefs['editor_theme']))
         self.highlighter.set_document(self)
         self.setPlainText(text)
 
@@ -118,7 +112,7 @@ def format_for_token(theme, cache, token):
 class PygmentsHighlighter(object):
 
     def __init__(self, text, lexer):
-        theme, cache = get_theme(), {}
+        theme, cache = get_theme(tprefs['editor_theme']), {}
         theme = {k:highlight_to_char_format(v) for k, v in theme.iteritems()}
         theme[None] = NULL_FMT
         def fmt(token):
diff --git a/src/calibre/gui2/tweak_book/diff/view.py b/src/calibre/gui2/tweak_book/diff/view.py
index e814e99e4b..1b705a2abd 100644
--- a/src/calibre/gui2/tweak_book/diff/view.py
+++ b/src/calibre/gui2/tweak_book/diff/view.py
@@ -26,9 +26,9 @@ from calibre import human_readable, fit_image
 from calibre.gui2 import info_dialog
 from calibre.gui2.tweak_book import tprefs
 from calibre.gui2.tweak_book.editor.text import PlainTextEdit, default_font_family, LineNumbers
-from calibre.gui2.tweak_book.editor.themes import theme_color
+from calibre.gui2.tweak_book.editor.themes import theme_color, get_theme
 from calibre.gui2.tweak_book.diff import get_sequence_matcher
-from calibre.gui2.tweak_book.diff.highlight import get_theme, get_highlighter
+from calibre.gui2.tweak_book.diff.highlight import get_highlighter
 
 Change = namedtuple('Change', 'ltop lbot rtop rbot kind')
 
@@ -119,7 +119,7 @@ class TextBrowser(PlainTextEdit):  # {{{
         font = self.heading_font = QFont(self.font())
         font.setPointSize(int(tprefs['editor_font_size'] * 1.5))
         font.setBold(True)
-        theme = get_theme()
+        theme = get_theme(tprefs['editor_theme'])
         pal = self.palette()
         pal.setColor(pal.Base, theme_color(theme, 'Normal', 'bg'))
         pal.setColor(pal.AlternateBase, theme_color(theme, 'CursorLine', 'bg'))
diff --git a/src/calibre/gui2/tweak_book/editor/text.py b/src/calibre/gui2/tweak_book/editor/text.py
index c0f2b59cdd..9c0c7b1778 100644
--- a/src/calibre/gui2/tweak_book/editor/text.py
+++ b/src/calibre/gui2/tweak_book/editor/text.py
@@ -19,7 +19,7 @@ from PyQt4.Qt import (
 from calibre import prepare_string_for_xml, xml_entity_to_unicode
 from calibre.gui2.tweak_book import tprefs, TOP
 from calibre.gui2.tweak_book.editor import SYNTAX_PROPERTY, SPELL_PROPERTY
-from calibre.gui2.tweak_book.editor.themes import THEMES, default_theme, theme_color, theme_format
+from calibre.gui2.tweak_book.editor.themes import get_theme, theme_color, theme_format
 from calibre.gui2.tweak_book.editor.syntax.base import SyntaxHighlighter
 from calibre.gui2.tweak_book.editor.syntax.html import HTMLHighlighter, XMLHighlighter
 from calibre.gui2.tweak_book.editor.syntax.css import CSSHighlighter
@@ -163,9 +163,7 @@ class TextEdit(PlainTextEdit):
     def apply_settings(self, prefs=None, dictionaries_changed=False):  # {{{
         prefs = prefs or tprefs
         self.setLineWrapMode(QPlainTextEdit.WidgetWidth if prefs['editor_line_wrap'] else QPlainTextEdit.NoWrap)
-        theme = THEMES.get(prefs['editor_theme'], None)
-        if theme is None:
-            theme = THEMES[default_theme()]
+        theme = get_theme(prefs['editor_theme'])
         self.apply_theme(theme)
         w = self.fontMetrics()
         self.space_width = w.width(' ')
diff --git a/src/calibre/gui2/tweak_book/editor/themes.py b/src/calibre/gui2/tweak_book/editor/themes.py
index 0b666007fa..ec4d102875 100644
--- a/src/calibre/gui2/tweak_book/editor/themes.py
+++ b/src/calibre/gui2/tweak_book/editor/themes.py
@@ -226,6 +226,12 @@ def u(x):
     return x + 'Underline'
 underline_styles = {x:getattr(SyntaxTextCharFormat, u(x)) for x in underline_styles}
 
+def get_theme(name):
+    try:
+        return THEMES[name]
+    except KeyError:
+        return THEMES[default_theme()]
+
 def highlight_to_char_format(h):
     ans = SyntaxTextCharFormat()
     if h.bold:
diff --git a/src/calibre/gui2/tweak_book/live_css.py b/src/calibre/gui2/tweak_book/live_css.py
index d3dcf815f6..9273eb9949 100644
--- a/src/calibre/gui2/tweak_book/live_css.py
+++ b/src/calibre/gui2/tweak_book/live_css.py
@@ -16,7 +16,7 @@ from PyQt4.Qt import (
 
 from calibre.constants import iswindows
 from calibre.gui2.tweak_book import editors, actions, current_container, tprefs
-from calibre.gui2.tweak_book.editor.themes import THEMES, default_theme, theme_color
+from calibre.gui2.tweak_book.editor.themes import get_theme, theme_color
 from calibre.gui2.tweak_book.editor.text import default_font_family
 
 class Heading(QWidget):  # {{{
@@ -359,9 +359,7 @@ class LiveCSS(QWidget):
         f.setFamily(tprefs['editor_font_family'] or default_font_family())
         f.setPointSize(tprefs['editor_font_size'])
         self.setFont(f)
-        theme = THEMES.get(tprefs['editor_theme'], None)
-        if theme is None:
-            theme = THEMES[default_theme()]
+        theme = get_theme(tprefs['editor_theme'])
         pal = self.palette()
         pal.setColor(pal.Window, theme_color(theme, 'Normal', 'bg'))
         pal.setColor(pal.WindowText, theme_color(theme, 'Normal', 'fg'))