diff --git a/.gitignore b/.gitignore
index 30f02d1c5af28706cb5c6e661bbaba59c5bf937e..a87719155a81c2d1398130f803674726ec831865 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,8 @@
 __pycache__
 .tox
+.eggs
 .coverage
 *cache.db
 *.egg-info
 .docker/cert
+src/caosadvancedtools/version.py
diff --git a/src/caosadvancedtools/crawler.py b/src/caosadvancedtools/crawler.py
index 7c4ae658c60a363e4d4ecfff0780acf1213b011f..e1d9901c60620b2d858f5f8bb54d346d1e87fe8d 100644
--- a/src/caosadvancedtools/crawler.py
+++ b/src/caosadvancedtools/crawler.py
@@ -224,8 +224,8 @@ class Crawler(object):
                 msg = ("The crawler has no matching rules for and is thus "
                        "ignoring:\n{}".format(item))
 
-                logging.warning(msg, extra={"identifier": str(item),
-                                            'category': "matches"})
+                logger.warning(msg, extra={"identifier": str(item),
+                                           'category': "matches"})
 
             if len(matches[idx]) > 1:
                 msg = ("Attention: More than one matching cfood!\n"
@@ -233,8 +233,8 @@ class Crawler(object):
                        + "\tRecordTypes:\t" + ", ".join(
                             matches[idx])+"\n")
 
-                logging.warning(msg, extra={"identifier": str(item),
-                                            'category': "matches"})
+                logger.warning(msg, extra={"identifier": str(item),
+                                           'category': "matches"})
 
     def cached_find_identifiables(self, identifiables):
         if self.use_cache:
diff --git a/src/caosadvancedtools/table_importer.py b/src/caosadvancedtools/table_importer.py
index 4ade13bd7495d1509041e4f005bd08f7ab34896a..6fb4a28f17420df901ad33a2bbe57fbd63dfc190 100755
--- a/src/caosadvancedtools/table_importer.py
+++ b/src/caosadvancedtools/table_importer.py
@@ -75,7 +75,8 @@ class TSV_Importer(object):
 
 
 class XLS_Importer(object):
-    def __init__(self, converters, obligatory_columns=[], unique_columns=[]):
+
+    def __init__(self, converters, obligatory_columns=None, unique_columns=None):
         """
         converters: dict with column names as keys and converter functions as
                     values
@@ -89,8 +90,8 @@ class XLS_Importer(object):
         """
         self.sup = SuppressKnown()
         self.required_columns = list(converters.keys())
-        self.obligatory_columns = obligatory_columns
-        self.unique_columns = unique_columns
+        self.obligatory_columns = [] if obligatory_columns is None else obligatory_columns
+        self.unique_columns = [] if unique_columns is None else unique_columns
         self.converters = converters
 
     def read_xls(self, filename):
@@ -161,9 +162,9 @@ class XLS_Importer(object):
         df = df.copy()
         uniques = []
 
-        for index, row in df.iterrows():
-            element = tuple(row.loc[key] for key in self.unique_columns)
-
+        subtable = df[list(self.unique_columns)]
+        for index, row in subtable.iterrows():
+            element = tuple(row)
             if element in uniques:
                 errmsg = (
                     "The {}. row contains the values '{}'.\nThis value "