diff --git a/src/calibre/ebooks/pml/pmlml.py b/src/calibre/ebooks/pml/pmlml.py
index f6f737275e..854bd7fa5c 100644
--- a/src/calibre/ebooks/pml/pmlml.py
+++ b/src/calibre/ebooks/pml/pmlml.py
@@ -174,8 +174,8 @@ class PMLMLizer(object):
         return text
 
     def prepare_text(self, text):
-        # Replace empty paragraphs with \c pml codes used to denote emtpy lines.
-        text = re.sub(unicode_type(r'(?<=</p>)\s*<p[^>]*>[\xc2\xa0\s]*</p>'), '\\c\n\\c', text)
+        # Replace empty paragraphs with \c pml codes used to denote empty lines.
+        text = re.sub(unicode_type(r'(?<=</p>)\s*<p[^>]*>[\xc2\xa0\s]*</p>'), r'\\c\n\\c', text)
         return text
 
     def clean_text(self, text):
@@ -207,7 +207,7 @@ class PMLMLizer(object):
         text = re.sub('[ ]{2,}', ' ', text)
 
         # Condense excessive \c empty line sequences.
-        text = re.sub('(\\c\\s*\\c\\s*){2,}', '\\c \n\\c\n', text)
+        text = re.sub(r'(\\c\\s*\\c\\s*){2,}', r'\\c \n\\c\n', text)
 
         # Remove excessive newlines.
         text = re.sub('\n[ ]+\n', '\n\n', text)