diff --git a/ngrams/term_frequencies.py b/ngrams/term_frequencies.py
index 9703f3c..c6d0be3 100755
--- a/ngrams/term_frequencies.py
+++ b/ngrams/term_frequencies.py
@@ -33,6 +33,9 @@ def remove_punct(sentence):
 def my_tokenizer(text, mwe_pass, mwe_tokenize, stopWords):
     # remove stopwords, punctuation, urls, lower case
     # lowercase        
+    if text is None:
+        return ""
+
     text = text.lower()
 
     # remove urls
@@ -122,7 +125,8 @@ def weekly_tf(partition,
         nullable_schema = False
     elif reddit_dataset == 'posts':
         tf_func = tf_posts
-        nullable_schema = True
+        nullable_schema = False
+        
     dataset = ds.dataset(f"{input_parquet}/{partition}", format='parquet')
     if not os.path.exists(output_10p_sample_path):
         os.mkdir(output_10p_sample_path)
@@ -209,6 +213,7 @@ def weekly_tf(partition,
             if table.shape[0] != 0:
                 writer.write_table(table)
                 do_break = False
+
             if author_table.shape[0] != 0:
                 author_writer.write_table(author_table)
                 do_break = False