diff --git a/whisper/decoding.py b/whisper/decoding.py
index 49485d0..312a9e0 100644
--- a/whisper/decoding.py
+++ b/whisper/decoding.py
@@ -169,7 +169,7 @@ class PyTorchInference(Inference):
         self.kv_cache = {}
         self.hooks = []
 
-    def rearrange_kv_cache(self, source_indices):
+    def rearrange_kv_cache(self, source_indices : List[int]):
         if source_indices != list(range(len(source_indices))):
             for module in self.kv_modules:
                 # update the key/value cache to contain the selected sequences