diff --git a/Chapter09_NaturalLanguages.ipynb b/Chapter09_NaturalLanguages.ipynb
index 5d90fa0..a44b4e3 100644
--- a/Chapter09_NaturalLanguages.ipynb
+++ b/Chapter09_NaturalLanguages.ipynb
@@ -18,7 +18,7 @@
     "from bs4 import BeautifulSoup\n",
     "import re\n",
     "import string\n",
-    "from collections import Counter\n",
+    "from collections import Counter, defaultdict\n",
     "\n",
     "def cleanSentence(sentence):\n",
     "    sentence = sentence.split(' ')\n",
@@ -187,13 +187,8 @@
     "    # Filter out empty words\n",
     "    words = [word for word in words if word != '']\n",
     "\n",
-    "    wordDict = {}\n",
+    "    wordDict = defaultdict(lambda: defaultdict(int))\n",
     "    for i in range(1, len(words)):\n",
-    "        if words[i-1] not in wordDict:\n",
-    "                # Create a new dictionary for this word\n",
-    "            wordDict[words[i-1]] = {}\n",
-    "        if words[i] not in wordDict[words[i-1]]:\n",
-    "            wordDict[words[i-1]][words[i]] = 0\n",
     "        wordDict[words[i-1]][words[i]] += 1\n",
     "    return wordDict\n",
     "\n",
@@ -305,8 +300,17 @@
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
    "version": "3.6.1"
+  },
+  "pycharm": {
+   "stem_cell": {
+    "cell_type": "raw",
+    "source": [],
+    "metadata": {
+     "collapsed": false
+    }
+   }
   }
  },
  "nbformat": 4,
  "nbformat_minor": 2
-}
+}
\ No newline at end of file