diff --git a/lib/wind/gen-normalize.py b/lib/wind/gen-normalize.py
index a5216e932..0955a54b9 100644
--- a/lib/wind/gen-normalize.py
+++ b/lib/wind/gen-normalize.py
@@ -51,7 +51,7 @@ ud = UnicodeData.read(sys.argv[1])
 
 def sortedKeys(d):
     """Return a sorted list of the keys of a dict"""
-    keys = d.keys()
+    keys = list(d.keys())
     keys.sort()
     return keys