diff --git a/sotawhat/sotawhat.py b/sotawhat/sotawhat.py
index 8c9d6f1..dbea437 100644
--- a/sotawhat/sotawhat.py
+++ b/sotawhat/sotawhat.py
@@ -97,7 +97,7 @@ def clean_empty_lines(lines):
 
 
 def is_float(token):
-    return re.match("^\d+?\.\d+?$", token) is not None
+    return re.match(r"^\d+?\.\d+?$", token) is not None
 
 
 def is_citation_year(tokens, i):