diff --git a/nlp/4_1_Lexical_Processing.ipynb b/nlp/4_1_Lexical_Processing.ipynb
index c16d584..25edad5 100644
--- a/nlp/4_1_Lexical_Processing.ipynb
+++ b/nlp/4_1_Lexical_Processing.ipynb
@@ -326,7 +326,7 @@
     "def preprocess(words, type='doc'):\n",
     "    if (type == 'tweet'):\n",
     "        tknzr = TweetTokenizer(strip_handles=True, reduce_len=True)\n",
-    "        tokens = tknzr.tokenize(tweet)\n",
+    "        tokens = tknzr.tokenize(words)\n",
     "    else:\n",
     "        tokens = nltk.word_tokenize(words.lower())\n",
     "    porter = nltk.PorterStemmer()\n",