diff --git a/wordfreq_builder/wordfreq_builder/tokenizers.py b/wordfreq_builder/wordfreq_builder/tokenizers.py
index fec5928..653fa7e 100644
--- a/wordfreq_builder/wordfreq_builder/tokenizers.py
+++ b/wordfreq_builder/wordfreq_builder/tokenizers.py
@@ -66,8 +66,8 @@ def tokenize_file(in_filename, out_prefix, tokenizer, line_reader=last_tab):
         for line in in_file:
             text = line_reader(line)
             tokens, language = tokenizer(text)
-            tokenized = '\n'.join(tokens)
             if language is not None:
+                tokenized = '\n'.join(tokens)
                 out_filename = '%s.%s.txt' % (out_prefix, language)
                 if out_filename in out_files:
                     out_file = out_files[out_filename]