diff --git a/lib/CoNLL_Annotation.py b/lib/CoNLL_Annotation.py
index 69bf4a7..1a8ddf0 100644
--- a/lib/CoNLL_Annotation.py
+++ b/lib/CoNLL_Annotation.py
@@ -187,8 +187,8 @@
     annotated_sentences, buffer_meta, buffer_lst = [], [], []
     for i, line in enumerate(line_generator):
         if line.startswith(comment_str):
-            line = re.sub("(foundry\s*=\s*).*", r"\1" + our_foundry, line)
-            line = re.sub("(filename\s*=\s* .[^/]*/[^/]+/[^/]+/).*", r"\1" + our_foundry + "/morpho.xml", line)
+            line = re.sub(r'(foundry\s*=\s*).*', r"\1" + our_foundry, line)
+            line = re.sub(r'(filename\s*=\s* .[^/]*/[^/]+/[^/]+/).*', r"\1" + our_foundry + "/morpho.xml", line)
             buffer_meta.append(line)
             continue
         if len(line.split()) > 0: