diff --git a/faster_whisper/tokenizer.py b/faster_whisper/tokenizer.py
index d75bbd7f..6f1a9b1d 100644
--- a/faster_whisper/tokenizer.py
+++ b/faster_whisper/tokenizer.py
@@ -32,7 +32,13 @@ def __init__(
                 )
 
             self.task = self.tokenizer.token_to_id("<|%s|>" % task)
+
             self.language = self.tokenizer.token_to_id("<|%s|>" % language)
+            if self.language is None:
+                raise ValueError(
+                    "Language '%s' is not supported by this model" % language
+                )
+
             self.language_code = language
         else:
             self.task = None