diff --git a/wikiedits/__init__.py b/wikiedits/__init__.py
index 7190ac1..9f38d8d 100644
--- a/wikiedits/__init__.py
+++ b/wikiedits/__init__.py
@@ -4,4 +4,6 @@
     'english',
     'polish',
     'german',
+    'slovak',
+    'ukrainian'
 ]
diff --git a/wikiedits/edit_filter.py b/wikiedits/edit_filter.py
index 4e89235..173516d 100644
--- a/wikiedits/edit_filter.py
+++ b/wikiedits/edit_filter.py
@@ -20,7 +20,10 @@ def __init__(self,
                  edit_ratio=0.3,
                  min_chars=10):
 
-        self.segmenter = nltk.data.load('tokenizers/punkt/%s.pickle' % lang)
+        if lang=='slovak':
+            self.segmenter = nltk.data.load('tokenizers/punkt/czech.pickle')
+        else:
+            self.segmenter = nltk.data.load('tokenizers/punkt/%s.pickle' % lang)
 
         self.LEVENSHTEIN_RATIO_LOG_BASE = 20
 
diff --git a/wikiedits/wiki/__init__.py b/wikiedits/wiki/__init__.py
index 641d69b..d17bcac 100644
--- a/wikiedits/wiki/__init__.py
+++ b/wikiedits/wiki/__init__.py
@@ -1,7 +1,10 @@
 #  -*- coding: utf-8 -*-
 
 VANDALISM_REGEXES = {
-    'english': "vandal|stupid|revert",
-    'polish': "anulowan|wycofan|cofnię|cofnie|przywróc|przywroc|revert|rewert",
-    'german': "revert|vandal|rückgängig",
+    'english': u"vandal|stupid|revert",
+    'polish': u"anulowan|wycofan|cofnię|cofnie|przywróc|przywroc|revert|rewert",
+    'german': u"revert|vandal|rückgängig",
+    'slovak': u"revert|vráten|vraten|vandal|obnov|revízia|revizia",
+    'ukrainian': u"відкинут|відміна редагування|скасування редагування|вандал",
+
 }
diff --git a/wikiedits/wiki/revision_iterator.py b/wikiedits/wiki/revision_iterator.py
index 2b2b3ee..86857c7 100644
--- a/wikiedits/wiki/revision_iterator.py
+++ b/wikiedits/wiki/revision_iterator.py
@@ -6,6 +6,7 @@
 import WikiExtractor
 import re
 
+
 HTML_TAG_REGEX = r'<[^>]{1,20}?>'
 
 class RevisionIterator(object):
@@ -48,6 +49,8 @@ def clean_markups(self, text):
         return "\n".join(clean_html) if len(clean_html) > 0 else ""
 
     def __is_revert_vandalism(self, comment):
-        if type(comment) is str:
+        if comment is not None:
             return bool(self.vandalism_regex.search(comment))
-        return False
+        else:
+            return False
+