diff --git a/preprocess.py b/preprocess.py
index 3778849..279632e 100755
--- a/preprocess.py
+++ b/preprocess.py
@@ -59,6 +59,7 @@ def prune_vocab(self, k, cnt = False):
 
     def load_vocab(self, vocab_file):
         self.d = {}
+        self.idx2word = {}
         for line in open(vocab_file, 'r'):
             v, k = line.strip().split()
             self.d[v] = int(k)