diff --git a/src/zopyx/convert2/calibre.py b/src/zopyx/convert2/calibre.py
index 4714c1b..c994e2c 100755
--- a/src/zopyx/convert2/calibre.py
+++ b/src/zopyx/convert2/calibre.py
@@ -16,9 +16,7 @@
 from tidy import tidyhtml
 
 def _check_calibre():
-    if not which('ebook-convert'):
-        return False
-    return True
+    return bool(which('ebook-convert'))
 
 calibre_available = _check_calibre()
 
@@ -26,7 +24,7 @@ def html2calibre(html_filename, output_filename=None, cmdopts='', **calibre_opti
     """ Convert a HTML file using calibre """
     
     if not html_filename.endswith('.html'):
-        shutil.copy(html_filename, html_filename + '.html')
+        shutil.copy(html_filename, f'{html_filename}.html')
         html_filename += '.html'
 
     if not output_filename:
@@ -35,23 +33,22 @@ def html2calibre(html_filename, output_filename=None, cmdopts='', **calibre_opti
     if not calibre_available:
         raise RuntimeError("The external calibre converter isn't available")
 
-    options = list()
+    options = []
     for k,v in calibre_options.items():
         if v is None:
-            options.append('--%s ' % k)
+            options.append(f'--{k} ')
         else:
             options.append('--%s="%s" ' % (k, v)) 
 
     if sys.platform == 'win32':
         raise NotImplementedError('No support for using Calibre on Windows available')
-    else:
-        options = ' '.join(options)
-        options = options + ' ' + cmdopts
-        cmd = '"ebook-convert" "%s" "%s" %s' % (html_filename, output_filename, options)
-    
+    options = ' '.join(options)
+    options = f'{options} {cmdopts}'
+    cmd = '"ebook-convert" "%s" "%s" %s' % (html_filename, output_filename, options)
+
     status, output = runcmd(cmd)
     if status != 0:
-        raise ConversionError('Error executing: %s' % cmd, output)
+        raise ConversionError(f'Error executing: {cmd}', output)
 
     return dict(output_filename=output_filename,
                 status=status,
diff --git a/src/zopyx/convert2/convert.py b/src/zopyx/convert2/convert.py
index b90649f..5867311 100755
--- a/src/zopyx/convert2/convert.py
+++ b/src/zopyx/convert2/convert.py
@@ -21,7 +21,7 @@ def convert(self, format, output_filename=None, options={}):
 
         converter = registry.converter_registry.get(format)
         if converter is None:
-            raise ValueError('Unsupported format: %s' % format)
+            raise ValueError(f'Unsupported format: {format}')
 
         if format == 'fo':
             c = converter()
@@ -61,7 +61,6 @@ def convert(self, format, output_filename=None, **options):
     def __del__(self):
         """ House-keeping """
 
-        if self.cleanup:
-            if self.fo_filename:
-                os.unlink(self.fo_filename)
+        if self.cleanup and self.fo_filename:
+            os.unlink(self.fo_filename)
 
diff --git a/src/zopyx/convert2/fo.py b/src/zopyx/convert2/fo.py
index b054caf..4a50682 100755
--- a/src/zopyx/convert2/fo.py
+++ b/src/zopyx/convert2/fo.py
@@ -40,15 +40,11 @@ def convert(self, filename, encoding='utf-8', tidy=True, output_filename=None, *
         if tidy:
             filename = tidyhtml(filename, encoding, strip_base=kw.get('strip_base', False))
 
-        if output_filename:
-            fo_filename = output_filename
-        else:
-            fo_filename = newTempfile(suffix='.fo')
-
+        fo_filename = output_filename or newTempfile(suffix='.fo')
         csstoxslfo = os.path.abspath(os.path.join(dirname, 'lib', 'csstoxslfo', 'css2xslfo.jar'))
         if not os.path.exists(csstoxslfo):
-            raise IOError('%s does not exist' % csstoxslfo)
-        
+            raise IOError(f'{csstoxslfo} does not exist')
+
         cmd = '"%s"' % java + \
               ' -Duser.language=en -Xms256m -Xmx256m -jar "%(csstoxslfo)s" "%(filename)s" -fo "%(fo_filename)s"' % vars()
         for k in kw:
@@ -56,7 +52,7 @@ def convert(self, filename, encoding='utf-8', tidy=True, output_filename=None, *
 
         status, output = runcmd(cmd)
         if status != 0:
-            raise ConversionError('Error executing: %s' % cmd, output)
+            raise ConversionError(f'Error executing: {cmd}', output)
 
         # remove tidy-ed file
         if tidy:
@@ -67,7 +63,7 @@ def convert(self, filename, encoding='utf-8', tidy=True, output_filename=None, *
 
         E = parse(fo_filename)
 
-        ids_seen = list()
+        ids_seen = []
         for node in E.getiterator():
             get = node.attrib.get
 
@@ -114,7 +110,7 @@ def convert(self, filename, encoding='utf-8', tidy=True, output_filename=None, *
                              'wrap-option' : 'no-wrap',
                              'linefeed-treatment' : 'preserve' }.items():
                     node.attrib[k] = v
-                
+
         fo_text = tostring(E.getroot())
         fo_text = fo_text.replace('<ns0:block ' , '<ns0:block margin-top="0" margin-bottom="0" ')  # avoid a linebreak through <li><p> (XFC)
 #        fo_text = fo_text.replace('<ns0:block/>', '') # causes a crash with XINC    
diff --git a/src/zopyx/convert2/fop.py b/src/zopyx/convert2/fop.py
index 3adace9..e5555fe 100755
--- a/src/zopyx/convert2/fop.py
+++ b/src/zopyx/convert2/fop.py
@@ -18,10 +18,10 @@ def _check_fop():
     if not checkEnvironment('FOP_HOME'):
         return False
 
-    exe_name = win32 and 'fop.bat' or 'fop'
+    exe_name = 'fop.bat' if win32 else 'fop'
     full_exe_name = os.path.join(fop_home, exe_name)
     if not os.path.exists(full_exe_name):
-        LOG.debug('%s does not exist' % full_exe_name)
+        LOG.debug(f'{full_exe_name} does not exist')
         return False
 
     return True
@@ -43,7 +43,7 @@ def fo2pdf(fo_filename, output_filename=None):
 
     status, output = runcmd(cmd)
     if status != 0:
-        raise ConversionError('Error executing: %s' % cmd, output)
+        raise ConversionError(f'Error executing: {cmd}', output)
 
     return dict(output_filename=output_filename,
                 status=status,
@@ -64,8 +64,7 @@ def available():
     def convert(self, output_filename=None, **options):
         options['strip_base'] = True
         self.convert2FO(**options)
-        result = fo2pdf(self.fo_filename, output_filename)
-        return result
+        return fo2pdf(self.fo_filename, output_filename)
 
 fop_available = _check_fop()
 
diff --git a/src/zopyx/convert2/pdfreactor.py b/src/zopyx/convert2/pdfreactor.py
index 9870cd7..6c57cbe 100644
--- a/src/zopyx/convert2/pdfreactor.py
+++ b/src/zopyx/convert2/pdfreactor.py
@@ -15,9 +15,7 @@
 from exceptions import ConversionError
 
 def _check_pdfreactor():
-    if not which('pdfreactor'):
-        return False
-    return True
+    return bool(which('pdfreactor'))
 
 pdfreactor_available = _check_pdfreactor()
 
@@ -32,10 +30,10 @@ def html2pdf(html_filename, output_filename=None, **options):
 
     cmd = '%s "pdfreactor" "%s" "%s"' % \
           (execution_shell, html_filename, output_filename)
-    
+
     status, output = runcmd(cmd)
     if status != 0:
-        raise ConversionError('Error executing: %s' % cmd, output)
+        raise ConversionError(f'Error executing: {cmd}', output)
     return dict(output_filename=output_filename,
                 status=status,
                 output=output)
diff --git a/src/zopyx/convert2/pisa.py b/src/zopyx/convert2/pisa.py
index d350157..3cbd9e2 100755
--- a/src/zopyx/convert2/pisa.py
+++ b/src/zopyx/convert2/pisa.py
@@ -47,8 +47,7 @@ def available():
         return True
 
     def convert(self, output_filename=None, **options):
-        result = html2pdf(self.filename, output_filename, **options)
-        return result
+        return html2pdf(self.filename, output_filename, **options)
 
 from registry import registerConverter
 registerConverter(HTML2PDF)
diff --git a/src/zopyx/convert2/pisa_bin.py b/src/zopyx/convert2/pisa_bin.py
index 31df42a..e414bf8 100755
--- a/src/zopyx/convert2/pisa_bin.py
+++ b/src/zopyx/convert2/pisa_bin.py
@@ -41,8 +41,7 @@ def available():
         return True
 
     def convert(self, output_filename=None, **options):
-        result = html2pdf(self.filename, output_filename, **options)
-        return result
+        return html2pdf(self.filename, output_filename, **options)
 
 from registry import registerConverter
 registerConverter(HTML2PDF)
diff --git a/src/zopyx/convert2/prince.py b/src/zopyx/convert2/prince.py
index 690e078..60102f7 100755
--- a/src/zopyx/convert2/prince.py
+++ b/src/zopyx/convert2/prince.py
@@ -15,9 +15,7 @@
 from exceptions import ConversionError
 
 def _check_prince():
-    if not which('prince'):
-        return False
-    return True
+    return bool(which('prince'))
 
 prince_available = _check_prince()
 
@@ -30,10 +28,10 @@ def html2pdf(html_filename, output_filename=None, **options):
     if not prince_available:
         raise RuntimeError("The external PrinceXML converter isn't available")
 
-    cmd_options = list()
+    cmd_options = []
     for k,v in options.items():
         if v is None:
-            cmd_options.append('--%s ' % k)
+            cmd_options.append(f'--{k} ')
         else:
             cmd_options.append('--%s="%s" ' % (k, v)) 
 
@@ -42,10 +40,10 @@ def html2pdf(html_filename, output_filename=None, **options):
     else:
         cmd = '%s "prince" "%s" %s -o "%s"' % \
               (execution_shell, html_filename, ' '.join(cmd_options), output_filename)
-    
+
     status, output = runcmd(cmd)
     if status != 0:
-        raise ConversionError('Error executing: %s' % cmd, output)
+        raise ConversionError(f'Error executing: {cmd}', output)
     return dict(output_filename=output_filename,
                 status=status,
                 output=output)
diff --git a/src/zopyx/convert2/registry.py b/src/zopyx/convert2/registry.py
index 1135870..3187305 100644
--- a/src/zopyx/convert2/registry.py
+++ b/src/zopyx/convert2/registry.py
@@ -8,8 +8,9 @@
 A simple converter registry
 """
 
+
 # map converter name to converter class
-converter_registry = dict()
+converter_registry = {}
 
 def registerConverter(converter_cls):
     converter_registry[converter_cls.name] = converter_cls
diff --git a/src/zopyx/convert2/tidy.py b/src/zopyx/convert2/tidy.py
index 64a8ad4..e819bc1 100755
--- a/src/zopyx/convert2/tidy.py
+++ b/src/zopyx/convert2/tidy.py
@@ -48,11 +48,10 @@ def handler(mo):
         """ Callback to convert entities """
         e = mo.group(1)
         v = e[1:-1]
-        if not v.startswith('#'):
-            codepoint =  name2codepoint.get(v)
-            return codepoint and '&#%d;' % codepoint or ''
-        else:
+        if v.startswith('#'):
             return e
+        codepoint =  name2codepoint.get(v)
+        return codepoint and '&#%d;' % codepoint or ''
     
     entity_reg = re.compile('(&.*?;)')
     html = entity_reg.sub(handler, html)
diff --git a/src/zopyx/convert2/util.py b/src/zopyx/convert2/util.py
index 94a9b81..6ead417 100755
--- a/src/zopyx/convert2/util.py
+++ b/src/zopyx/convert2/util.py
@@ -71,7 +71,7 @@ def checkEnvironment(envname):
 
     dirname = os.environ.get(envname, None)
     if dirname is None:
-        LOG.debug('Environment variable $%s is unset' % envname)
+        LOG.debug(f'Environment variable ${envname} is unset')
         return False
 
     if not os.path.exists(dirname):
diff --git a/src/zopyx/convert2/xfc.py b/src/zopyx/convert2/xfc.py
index a27d6c8..4448cd2 100755
--- a/src/zopyx/convert2/xfc.py
+++ b/src/zopyx/convert2/xfc.py
@@ -22,7 +22,7 @@ def _check_xfc():
     # converters are also installed properly)
     full_exe_name = os.path.join(xfc_dir, 'fo2rtf')
     if not os.path.exists(full_exe_name):
-        LOG.debug('%s does not exist' % full_exe_name)
+        LOG.debug(f'{full_exe_name} does not exist')
         return False
 
     return True
@@ -33,11 +33,11 @@ def fo2xfc(fo_filename, format='rtf', output_filename=None):
         through XFC-4.0.
     """
 
-    if not format in ('rtf', 'docx', 'wml', 'odt'):
-        raise ValueError('Unsupported format: %s' % format)
+    if format not in ('rtf', 'docx', 'wml', 'odt'):
+        raise ValueError(f'Unsupported format: {format}')
 
     if not output_filename:
-        output_filename = newTempfile(suffix='.%s' % format)
+        output_filename = newTempfile(suffix=f'.{format}')
 
     if sys.platform == 'win32':
         cmd = '"%s\\fo2%s.bat"  "%s" "%s"' % (xfc_dir, format, fo_filename, output_filename) 
@@ -47,7 +47,7 @@ def fo2xfc(fo_filename, format='rtf', output_filename=None):
 
     status, output = runcmd(cmd)
     if status != 0:
-        raise ConversionError('Error executing: %s' % cmd, output)
+        raise ConversionError(f'Error executing: {cmd}', output)
 
     return dict(output_filename=output_filename,
                 status=status,
diff --git a/src/zopyx/convert2/xinc.py b/src/zopyx/convert2/xinc.py
index d19ae11..e932de8 100755
--- a/src/zopyx/convert2/xinc.py
+++ b/src/zopyx/convert2/xinc.py
@@ -19,10 +19,10 @@ def _check_xinc():
     if not checkEnvironment('XINC_HOME'):
         return False
 
-    exe_name = win32 and '\\bin\\windows\\xinc.exe' or 'bin/unix/xinc'
+    exe_name = '\\bin\\windows\\xinc.exe' if win32 else 'bin/unix/xinc'
     full_exe_name = os.path.join(xinc_home, exe_name)
     if not os.path.exists(full_exe_name):
-        LOG.debug('%s does not exist' % full_exe_name)
+        LOG.debug(f'{full_exe_name} does not exist')
         return False
 
     return True
@@ -43,7 +43,7 @@ def fo2pdf(fo_filename, output_filename=None):
 
     status, output = runcmd(cmd)
     if status != 0:
-        raise ConversionError('Error executing: %s' % cmd, output)
+        raise ConversionError(f'Error executing: {cmd}', output)
     return dict(output_filename=output_filename,
                 status=status,
                 output=output)
@@ -63,8 +63,7 @@ def available():
 
     def convert(self, output_filename=None, **options):
         self.convert2FO(**options)
-        result = fo2pdf(self.fo_filename, output_filename)
-        return result
+        return fo2pdf(self.fo_filename, output_filename)
 
 
 xinc_available = _check_xinc()