diff --git a/sphinx/util/__init__.py b/sphinx/util/__init__.py
index c1e8d25c9..2ef420ed1 100644
--- a/sphinx/util/__init__.py
+++ b/sphinx/util/__init__.py
@@ -162,19 +162,22 @@ def copy_static_entry(source, targetdir, builder, context={},
             shutil.copytree(source, target)
 
 
+_DEBUG_HEADER = '''\
+# Sphinx version: %s
+# Docutils version: %s %s
+# Jinja2 version: %s
+'''
+
 def save_traceback():
     """
     Save the current exception's traceback in a temporary file.
     """
     exc = traceback.format_exc()
     fd, path = tempfile.mkstemp('.log', 'sphinx-err-')
-    os.write(fd,
-        (('# Sphinx version: %s\n'
-          '# Docutils version: %s %s\n'
-          '# Jinja2 version: %s\n') % (sphinx.__version__,
-                                       docutils.__version__,
-                                       docutils.__version_details__,
-                                       jinja2.__version__)).encode('utf-8'))
+    os.write(fd, (_DEBUG_HEADER %
+                  (sphinx.__version__,
+                   docutils.__version__, docutils.__version_details__,
+                   jinja2.__version__)).encode('utf-8'))
     os.write(fd, exc.encode('utf-8'))
     os.close(fd)
     return path