diff --git a/evoprompt/models.py b/evoprompt/models.py
index 565ce89f9e36e18f10370f074e51364d9c088e16..4e7b36116239317d849d77b5ae8202ea137447f6 100644
--- a/evoprompt/models.py
+++ b/evoprompt/models.py
@@ -133,7 +133,7 @@ class LLMModel(ABC):
             sort_keys=True,
         )
         cache_key = (
-            str(self.model_name) + hashlib.sha1(unique_options_key.encode()).hexdigest()
+            str(self.model_name) + '/' + hashlib.sha1(unique_options_key.encode()).hexdigest()
         )
         return cache_key