diff --git a/pyopencl/tools.py b/pyopencl/tools.py
index 262da225f0a42ed4e79b9c9213267e80e7c46ec0..67302d8a970217a6473087eaf400f47ee8eaf141 100644
--- a/pyopencl/tools.py
+++ b/pyopencl/tools.py
@@ -86,7 +86,8 @@ def first_arg_dependent_memoize(func):
         if kwargs:
             cache_key = (args, frozenset(kwargs.items()))
         else:
-            cache_key = args
+            cache_key = (args,)
+
         try:
             ctx_dict = func._pyopencl_first_arg_dep_memoize_dic
         except AttributeError: