diff --git a/src/calibre/gui2/dbus_export/gtk.py b/src/calibre/gui2/dbus_export/gtk.py
index 8d40c0dfce..da82d6a0a6 100644
--- a/src/calibre/gui2/dbus_export/gtk.py
+++ b/src/calibre/gui2/dbus_export/gtk.py
@@ -208,28 +208,24 @@ class MyApplication(Gtk.Application):
         conn = xcb.Connection()
         atoms = conn.core.ListProperties(win_id).reply().atoms
         atom_names = {atom:conn.core.GetAtomNameUnchecked(atom) for atom in atoms}
-        atom_names = {k:str(a.reply().name.buf()) for k, a in atom_names.iteritems()}
+        atom_names = {k:bytes(a.reply().name.buf()) for k, a in atom_names.iteritems()}
         property_names = {name:atom for atom, name in atom_names.iteritems() if
             name.startswith('_GTK') or name.startswith('_UNITY') or name.startswith('_GNOME')}
         replies = {name:conn.core.GetProperty(False, win_id, atom, xcb.xproto.GetPropertyType.Any, 0, 2 ** 32 - 1) for name, atom in property_names.iteritems()}
 
+        type_atom_cache = {}
+
         def get_property_value(property_reply):
             if property_reply.format == 8:
-                if 0 in property_reply.value[:-1]:
-                    ret = []
-                    s = []
-                    for o in property_reply.value:
-                        if o == 0:
-                            ret.append(''.join(s))
-                            s = []
-                        else:
-                            s.append(chr(o))
-                else:
-                    ret = str(property_reply.value.buf())
-                    if len(property_reply.value) > 0 and 0 == property_reply.value[-1]:
-                        ret = ret[:-1]
-
-                return ret
+                is_list_of_strings = 0 in property_reply.value[:-1]
+                ans = bytes(property_reply.value.buf())
+                if property_reply.type not in type_atom_cache:
+                    type_atom_cache[property_reply.type] = bytes(conn.core.GetAtomNameUnchecked(property_reply.type).reply().name.buf())
+                if type_atom_cache[property_reply.type] == b'UTF8_STRING':
+                    ans = ans.decode('utf-8')
+                if is_list_of_strings:
+                    ans = ans.split('\0')
+                return ans
             elif property_reply.format in (16, 32):
                 return list(struct.unpack(b'I' * property_reply.value_len,
                                         property_reply.value.buf()))
diff --git a/src/calibre/gui2/dbus_export/utils.py b/src/calibre/gui2/dbus_export/utils.py
index 72b60d6c22..48a443cd2b 100644
--- a/src/calibre/gui2/dbus_export/utils.py
+++ b/src/calibre/gui2/dbus_export/utils.py
@@ -129,10 +129,19 @@ def setup_for_cli_run():
     signal.signal(signal.SIGINT, signal.SIG_DFL)  # quit on Ctrl-C
 
 def set_X_window_properties(win_id, **properties):
+    ' Set X Window properties on the window with the specified id. Only string values are supported. '
     import xcb, xcb.xproto
     conn = xcb.connect()
+    atoms = {name:conn.core.InternAtom(False, len(name), name) for name in properties}
+    utf8_string_atom = None
     for name, val in properties.iteritems():
-        atom = conn.core.InternAtom(False, len(name), name).reply().atom
-        conn.core.ChangePropertyChecked(xcb.xproto.PropMode.Replace, win_id, atom, xcb.xproto.Atom.STRING, 8, len(val), val)
+        atom = atoms[name].reply().atom
+        type_atom = xcb.xproto.Atom.STRING
+        if isinstance(val, unicode):
+            if utf8_string_atom is None:
+                utf8_string_atom = conn.core.InternAtom(True, len(b'UTF8_STRING'), b'UTF8_STRING').reply().atom
+            type_atom = utf8_string_atom
+            val = val.encode('utf-8')
+        conn.core.ChangePropertyChecked(xcb.xproto.PropMode.Replace, win_id, atom, type_atom, 8, len(val), val)
     conn.flush()
     conn.disconnect()