diff --git a/src/allmydata/introducer.py b/src/allmydata/introducer.py
index d5c4a306f..c7618867d 100644
--- a/src/allmydata/introducer.py
+++ b/src/allmydata/introducer.py
@@ -7,7 +7,7 @@ from twisted.application import service
 from twisted.python import log
 from foolscap import Referenceable
 from allmydata.interfaces import RIIntroducer, RIIntroducerClient
-from allmydata.util import idlib, observer
+from allmydata.util import observer
 
 class Introducer(service.MultiService, Referenceable):
     implements(RIIntroducer)
diff --git a/src/allmydata/node.py b/src/allmydata/node.py
index 41ef9c690..4c24f18d5 100644
--- a/src/allmydata/node.py
+++ b/src/allmydata/node.py
@@ -1,4 +1,4 @@
-from base64 import b32encode, b32decode
+from base64 import b32encode
 
 import os.path, re
 
diff --git a/src/allmydata/test/test_introducer.py b/src/allmydata/test/test_introducer.py
index bbdc47d71..b63b79ca4 100644
--- a/src/allmydata/test/test_introducer.py
+++ b/src/allmydata/test/test_introducer.py
@@ -1,4 +1,4 @@
-from base64 import b32encode, b32decode
+from base64 import b32encode
 
 from twisted.trial import unittest
 from twisted.internet import defer, reactor
diff --git a/src/allmydata/util/idlib.py b/src/allmydata/util/idlib.py
index 0f89a33c3..75b92aa1f 100644
--- a/src/allmydata/util/idlib.py
+++ b/src/allmydata/util/idlib.py
@@ -1,7 +1,7 @@
 # from the Python Standard Library
 import string
 
-from assertutil import _assert, precondition
+from assertutil import precondition
 
 z_base_32_alphabet = "ybndrfg8ejkmcpqxot1uwisza345h769" # Zooko's choice, rationale in "DESIGN" doc
 rfc3548_alphabet = "abcdefghijklmnopqrstuvwxyz234567" # RFC3548 standard used by Gnutella, Content-Addressable Web, THEX, Bitzi, Web-Calculus...