diff --git a/respodns/util.py b/respodns/util.py
index b1b4787..f41ef1f 100644
--- a/respodns/util.py
+++ b/respodns/util.py
@@ -1,8 +1,8 @@
 rot13_mapping = {}
 for a, b, c, d in zip("anAN05", "mzMZ49", "naNA50", "zmZM94"):
-    rot13_mapping.update(dict((chr(k), chr(v))
-                              for k, v in zip(range(ord(a), ord(b) + 1),
-                                              range(ord(c), ord(d) + 1))))
+    rot13_mapping.update({chr(k): chr(v)
+                          for k, v in zip(range(ord(a), ord(b) + 1),
+                                          range(ord(c), ord(d) + 1))})
 
 
 def rot13(s):