diff --git a/fastai_contrib/utils.py b/fastai_contrib/utils.py
index c7eb129..2c814ce 100644
--- a/fastai_contrib/utils.py
+++ b/fastai_contrib/utils.py
@@ -70,7 +70,7 @@ full_char_coverage_langs = ["bg", "cs", "da", "de", "el", "en", "es", "et", "fi"
                        "it","lt","lv","mt","nl","pl","pt","ro","sk","sl","sv"] # all European langus
 
 def get_sentencepiece(cache_dir:PathOrStr, load_text, pre_rules: ListRules=None, post_rules:ListRules=None,
-                      vocab_size:int=30000, model_type:str='unigram', input_sentence_size:int=1E7, lang='en'):
+                      vocab_size:int=30000, model_type:str='unigram', input_sentence_size:int=1E7, lang='en', fixed_character_coverage=False):
     try:
         import sentencepiece as spm
     except ImportError:
@@ -96,7 +96,10 @@ def get_sentencepiece(cache_dir:PathOrStr, load_text, pre_rules: ListRules=None,
         raw_text_path = cache_dir / 'all_text.txt'
         with open(raw_text_path, 'w') as f: f.write("\n".join(text))
 
-        char_coverage = 1 if lang in full_char_coverage_langs else 0.99
+        if fixed_character_coverage:
+            char_coverage = 0.9995
+        else:
+            char_coverage = 1 if lang in full_char_coverage_langs else 0.99
 
         sp_params = [
             f"--input={raw_text_path}",