diff --git a/memory.py b/memory.py
index 5281380..b5989da 100644
--- a/memory.py
+++ b/memory.py
@@ -22,7 +22,7 @@ def keepOnlyAlphaChars(word):
 
 def index(text):
     words = re.split('\s', text)
-    normalized_words = [keepOnlyAlphaChars(word) for word in words]
+    normalized_words = [keepOnlyAlphaChars(word).lower() for word in words]
     important_words = set([w for w in normalized_words
                              if len(w) >= WORD_LENGTH_THRESHOLD])
     return important_words