diff --git a/src/calibre/ebooks/oeb/reader.py b/src/calibre/ebooks/oeb/reader.py
index c1961ed0e2..bcdade1eec 100644
--- a/src/calibre/ebooks/oeb/reader.py
+++ b/src/calibre/ebooks/oeb/reader.py
@@ -632,7 +632,7 @@ class OEBReader(object):
             path = os.path.join(tdir, unquote(hcover.href))
             data = render_html_svg_workaround(path, self.logger)
             if not data:
-                data = ''
+                data = b''
         id, href = self.oeb.manifest.generate('cover', 'cover.jpg')
         item = self.oeb.manifest.add(id, href, JPEG_MIME, data=data)
         return item
diff --git a/src/calibre/ebooks/oeb/stylizer.py b/src/calibre/ebooks/oeb/stylizer.py
index d834e26ad3..109cccd06f 100644
--- a/src/calibre/ebooks/oeb/stylizer.py
+++ b/src/calibre/ebooks/oeb/stylizer.py
@@ -1,9 +1,9 @@
 # -*- encoding: utf-8 -*-
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 '''
 CSS property propagation class.
 '''
-from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2008, Marshall T. Vandegrift <llasram@gmail.com>'
@@ -33,7 +33,7 @@ def html_css_stylesheet():
     global _html_css_stylesheet
     if _html_css_stylesheet is None:
         with open(P('templates/html.css'), 'rb') as f:
-            html_css = f.read()
+            html_css = f.read().decode('utf-8')
         _html_css_stylesheet = parseString(html_css, validate=False)
     return _html_css_stylesheet
 
@@ -96,6 +96,7 @@ def test_media_ok():
     assert media_ok('screen, (device-width:10px)')
     assert not media_ok('screen and (device-width:10px)')
 
+
 class StylizerRules(object):
 
     def __init__(self, opts, profile, stylesheets):
@@ -181,6 +182,7 @@ class StylizerRules(object):
                 return False
         return True
 
+
 class Stylizer(object):
     STYLESHEETS = WeakKeyDictionary()
 
@@ -280,7 +282,7 @@ class Stylizer(object):
                     stylesheet = parser.parseString(text, href=cssname,
                             validate=False)
                     stylesheets.append(stylesheet)
-                except:
+                except Exception:
                     self.logger.exception('Failed to parse %s, ignoring.'%w)
                     self.logger.debug('Bad css: ')
                     self.logger.debug(x)
diff --git a/src/calibre/ebooks/oeb/transforms/htmltoc.py b/src/calibre/ebooks/oeb/transforms/htmltoc.py
index bab65763b8..df6f69925e 100644
--- a/src/calibre/ebooks/oeb/transforms/htmltoc.py
+++ b/src/calibre/ebooks/oeb/transforms/htmltoc.py
@@ -1,7 +1,7 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
 '''
 HTML-TOC-adding transform.
 '''
-from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2008, Marshall T. Vandegrift <llasram@gmail.com>'
diff --git a/src/calibre/ebooks/oeb/transforms/manglecase.py b/src/calibre/ebooks/oeb/transforms/manglecase.py
index c3a198949c..24c1a9aaca 100644
--- a/src/calibre/ebooks/oeb/transforms/manglecase.py
+++ b/src/calibre/ebooks/oeb/transforms/manglecase.py
@@ -1,7 +1,7 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
 '''
 CSS case-mangling transform.
 '''
-from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2008, Marshall T. Vandegrift <llasram@gmail.com>'
diff --git a/src/calibre/ebooks/oeb/transforms/rasterize.py b/src/calibre/ebooks/oeb/transforms/rasterize.py
index 83651b23e5..cfa320e85f 100644
--- a/src/calibre/ebooks/oeb/transforms/rasterize.py
+++ b/src/calibre/ebooks/oeb/transforms/rasterize.py
@@ -1,7 +1,7 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
 '''
 SVG rasterization transform.
 '''
-from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2008, Marshall T. Vandegrift <llasram@gmail.com>'