@@ -22,7 +22,7 @@ before_install:

 script:

 - cd tests

-- xvfb-run -a -s '-screen 0 1024x768x24' python ../test.py *.dot graphs/*.gv

+- LANG=C xvfb-run -a -s '-screen 0 1024x768x24' python ../test.py *.dot graphs/*.gv

 - cd ..

 # https://docs.travis-ci.com/user/deployment/pypi/

@@ -124,8 +124,8 @@ class DotWidget(Gtk.DrawingArea):

     def set_dotcode(self, dotcode, filename=None):

         self.openfilename = None

-        if isinstance(dotcode, str):

-            dotcode = dotcode.encode('utf-8')

+        # By default DOT language is UTF-8, but it accepts other encodings

+        assert isinstance(dotcode, bytes)

         xdotcode = self.run_filter(dotcode)

         if xdotcode is None:

             return False

@@ -151,7 +151,7 @@ class DotWidget(Gtk.DrawingArea):

     def reload(self):

         if self.openfilename is not None:

             try:

-                fp = open(self.openfilename, 'rt')

+                fp = open(self.openfilename, 'rb')

                 self.set_dotcode(fp.read(), self.openfilename)

                 fp.close()

             except IOError:

@@ -607,7 +607,7 @@ class DotWindow(Gtk.Window):

     def open_file(self, filename):

         try:

-            fp = open(filename, 'rt')

+            fp = open(filename, 'rb')

             self.set_dotcode(fp.read(), filename)

             fp.close()

         except IOError as ex: