diff --git a/libmat2/pdf.py b/libmat2/pdf.py
index cc83812558269b3cc6bb3f77a6a928b3c876eb88..2fe2b6bde4f4cd3b6730dc759c69ae3b3a74ffff 100644
--- a/libmat2/pdf.py
+++ b/libmat2/pdf.py
@@ -128,8 +128,8 @@ class PDFParser(abstract.AbstractParser):
         # It should(tm) be alright though, because cairo's output format
         # for metadata is fixed.
         with open(out_file, 'rb') as f:
-            out = re.sub(b'<<[\s\n]*/Producer.*?>>', b' << >>', f.read(), 0,
-                    re.DOTALL | re.IGNORECASE)
+            out = re.sub(rb'<<[\s\n]*/Producer.*?>>', b' << >>', f.read(), 0,
+                         re.DOTALL | re.IGNORECASE)
         with open(out_file, 'wb') as f:
             f.write(out)