diff --git a/outlines/caching.py b/outlines/caching.py
index 6fdda6214..3e58c7c16 100644
--- a/outlines/caching.py
+++ b/outlines/caching.py
@@ -126,7 +126,7 @@ def wrapper(*args, **kwargs):
 
         def __cache_key__(*args, **kwargs):
             """Make key for cache given function arguments."""
-            return args_to_key(base, args, kwargs, typed, ignore)
+            return str(args_to_key(base, args, kwargs, typed, ignore))
 
         wrapper.__cache_key__ = __cache_key__  # type: ignore
         wrapper.__memory__ = memory  # type: ignore
diff --git a/tests/test_cache.py b/tests/test_cache.py
index eb4ec406e..4492ed58a 100644
--- a/tests/test_cache.py
+++ b/tests/test_cache.py
@@ -1,3 +1,4 @@
+from dataclasses import dataclass
 import os
 import tempfile
 import unittest
@@ -68,6 +69,33 @@ def f(x):
     assert len(store) == store_size + 1
 
 
+def test_get_cache_from_class_method(test_cache):
+    store = list()
+
+    class DummyObject:
+        @classmethod
+        @test_cache
+        def dummy_function(cls, a):
+            store.append(a)
+            return a
+
+    @dataclass
+    class DummyArg:
+        a: int
+
+    dummy_object = DummyObject()
+
+    a_1 = DummyArg(1)
+
+    dummy_object.dummy_function(a_1)
+    assert len(store) == 1
+    store_size = len(store)
+
+    a_2 = DummyArg(1)
+    dummy_object.dummy_function(a_2)
+    assert len(store) == store_size
+
+
 def test_disable_cache(test_cache):
     """Make sure that we can disable the cache."""
     import outlines