diff --git a/src/metagger/pos_tagger.py.in b/src/metagger/pos_tagger.py.in
index 927248098e3fab8acf3fbeaf806ecbe4710db4c4..e60b0060b12e98c973536ac05295e6a95db08d2b 100755
--- a/src/metagger/pos_tagger.py.in
+++ b/src/metagger/pos_tagger.py.in
@@ -21,7 +21,7 @@ class POSTagger:
 
 
     def __init__(self):
-        self.known_words = []
+        self.known_words = {}
         self.tag_dict = {}
         self.lefff_dict = defaultdict(list)
         self.classifier = MegamClassifier()