diff --git a/src/calibre/utils/speedups.py b/src/calibre/utils/speedups.py
index 503d7d7557..31db62b7c3 100644
--- a/src/calibre/utils/speedups.py
+++ b/src/calibre/utils/speedups.py
@@ -4,10 +4,9 @@
 
 
 import os
-from polyglot.builtins import range, unicode_type
 
 
-class ReadOnlyFileBuffer(object):
+class ReadOnlyFileBuffer:
 
     ''' A zero copy implementation of a file like object. Uses memoryviews for efficiency. '''
 
@@ -68,7 +67,7 @@ def svg_path_to_painter_path(d):
     # x1/y1 and x2/y2 = bezier control points
     x = y = x1 = y1 = x2 = y2 = 0
 
-    if isinstance(d, unicode_type):
+    if isinstance(d, str):
         d = d.encode('ascii')
     d = d.replace(b',', b' ').replace(b'\n', b' ')
     end = len(d)