diff --git a/Tools/scripts/dutree.py b/Tools/scripts/dutree.py
index c51f105..dbf4f1a 100755
--- a/Tools/scripts/dutree.py
+++ b/Tools/scripts/dutree.py
@@ -25,7 +25,7 @@
 def store(size, comps, total, d):
     if comps == []:
         return size, d
-    if not d.has_key(comps[0]):
+    if comps[0] not in d:
         d[comps[0]] = None, {}
     t1, d1 = d[comps[0]]
     d[comps[0]] = store(size, comps[1:], t1, d1)
@@ -53,7 +53,7 @@
         else:
             print(prefix + repr(tsub).rjust(width) + ' ' + key)
             psub = prefix + ' '*(width-1) + '|' + ' '*(len(key)+1)
-        if d.has_key(key):
+        if key in d:
             show(tsub, d[key][1], psub)
 
 if __name__ == '__main__':