diff --git a/word_language_model/model.py b/word_language_model/model.py
index 4947d93617..39ab2693ff 100644
--- a/word_language_model/model.py
+++ b/word_language_model/model.py
@@ -26,6 +26,8 @@ def __init__(self, rnn_type, ntoken, ninp, nhid, nlayers, dropout=0.5, tie_weigh
         # "Tying Word Vectors and Word Classifiers: A Loss Framework for Language Modeling" (Inan et al. 2016)
         # https://arxiv.org/abs/1611.01462
         if tie_weights:
+            if nhid != ninp:
+                raise ValueError('When using the tied flag, nhid must be equal to emsize')
             self.decoder.weight = self.encoder.weight
 
         self.init_weights()