diff --git a/openlp/core/ui/thememanager.py b/openlp/core/ui/thememanager.py
index 6b43f2496..7c9fc073d 100644
--- a/openlp/core/ui/thememanager.py
+++ b/openlp/core/ui/thememanager.py
@@ -44,7 +44,7 @@ from openlp.core.lib.ui import UiStrings, critical_error_message_box, \
 from openlp.core.theme import Theme
 from openlp.core.ui import FileRenameForm, ThemeForm
 from openlp.core.utils import AppLocation, delete_file, file_is_unicode, \
-    file_is_mbcs, get_filesystem_encoding
+    get_filesystem_encoding
 
 log = logging.getLogger(__name__)
 
@@ -526,15 +526,11 @@ class ThemeManager(QtGui.QWidget):
             zip = zipfile.ZipFile(filename)
             themename = None
             for file in zip.namelist():
+                # Handle UTF-8 files
                 ucsfile = file_is_unicode(file)
                 if not ucsfile:
-                    ucsfile = file_is_mbcs(file)
-                    if not ucsfile:
-                        critical_error_message_box(
-                            message=translate('OpenLP.ThemeManager',
-                            'File is not a valid theme.\n'
-                            'The content encoding is not UTF-8.'))
-                        continue
+                    # Handle native Unicode files from Windows
+                    ucsfile = file
                 osfile = unicode(QtCore.QDir.toNativeSeparators(ucsfile))
                 theme_dir = None
                 if osfile.endswith(os.path.sep):
diff --git a/openlp/core/utils/__init__.py b/openlp/core/utils/__init__.py
index 9aa1acde6..fbf185474 100644
--- a/openlp/core/utils/__init__.py
+++ b/openlp/core/utils/__init__.py
@@ -475,26 +475,6 @@ def file_is_unicode(filename):
         return None
     return ucsfile
 
-def file_is_mbcs(filename):
-    """
-    Checks if a file is valid Windows file system encoded unicode and returns
-    the unicode decoded file or None.
-
-    ``filename``
-        File to check is valid Windows file system encoded.
-    """
-    if not filename:
-        return None
-    ucsfile = None
-    try:
-        ucsfile = filename.decode(u'mbcs')
-    except UnicodeDecodeError:
-        log.exception(u'Filename "%s" is not valid Windows encoded file' %
-            filename.decode(u'mbcs', u'replace'))
-    if not ucsfile:
-        return None
-    return ucsfile
-
 def get_uno_command():
     """
     Returns the UNO command to launch an openoffice.org instance.