diff --git a/rapids/models.py b/rapids/models.py
index 0eeeb10c..996a56a2 100644
--- a/rapids/models.py
+++ b/rapids/models.py
@@ -37,9 +37,9 @@ def image_directory_path(instance, filename):
     return u"rapids/picture/{0}".format(filename)
 
 
-def get_answer_compare(string):
-    s = string.strip().lower()
-    s = s.translate(str.maketrans('', '', string.punctuation.replace("#", "")))
+def get_answer_compare(s):
+    s = s.strip().lower()
+    s = s.translate(str.maketrans('', '', s.punctuation.replace("#", "")))
     return s
 
 class Abnormality(models.Model):