diff --git a/ulmfit/pretrain_lm.py b/ulmfit/pretrain_lm.py
index da14833..95a8068 100644
--- a/ulmfit/pretrain_lm.py
+++ b/ulmfit/pretrain_lm.py
@@ -98,7 +98,7 @@ class LMHyperParams:
         self.dps = np.array(self.dps)
         if self.nh is None: self.nh = 1550 if self.qrnn else 1150
         if self.name is None: self.name = self.lang
-        self.tokenizer = Tokenizers[self.tokenizer] if type(self.tokenizer) is str else self.tokenizer
+        self.tokenizer = Tokenizers[self.tokenizer] if isinstance(self.tokenizer, str) else self.tokenizer
 
     @property
     def tokenizer_prefix(self): return f"{self.tokenizer.value}{self.max_vocab // 1000}k"