diff --git a/lib/transaction.py b/lib/transaction.py
index 57339849c..6d1eee1d0 100644
--- a/lib/transaction.py
+++ b/lib/transaction.py
@@ -24,6 +24,7 @@ import bitcoin
 from bitcoin import *
 from util import print_error
 import time
+import sys
 import struct
 
 #
diff --git a/lib/util.py b/lib/util.py
index 3003a0c7c..22dc3887c 100644
--- a/lib/util.py
+++ b/lib/util.py
@@ -45,7 +45,10 @@ class DaemonThread(threading.Thread):
             self.running = False
 
     def print_error(self, *msg):
-        print_error("[%s]"%self.__class__.__name__, *msg)
+        print_error("[%s]" % self.__class__.__name__, *msg)
+
+    def print_msg(self, *msg):
+        print_msg("[%s]" % self.__class__.__name__, *msg)
 
 
 
diff --git a/lib/verifier.py b/lib/verifier.py
index b221856aa..35a8a6395 100644
--- a/lib/verifier.py
+++ b/lib/verifier.py
@@ -92,7 +92,7 @@ class SPV(util.DaemonThread):
 
 
     def undo_verifications(self, height):
-        tx_hashes = selt.wallet.undo_verifications(height)
+        tx_hashes = self.wallet.undo_verifications(height)
         for tx_hash in tx_hashes:
             self.print_error("redoing", tx_hash)
             self.merkle_roots.pop(tx_hash, None)