diff --git a/pyopencl/invoker.py b/pyopencl/invoker.py
index c2cbbfdad..8d3c44530 100644
--- a/pyopencl/invoker.py
+++ b/pyopencl/invoker.py
@@ -375,7 +375,8 @@ def _check_arg_size(function_name, num_cl_args, arg_types, devs):
 
 invoker_cache = WriteOncePersistentDict(
         "pyopencl-invoker-cache-v41",
-        key_builder=_NumpyTypesKeyBuilder())
+        key_builder=_NumpyTypesKeyBuilder(),
+        in_mem_cache_size=0)
 
 
 def generate_enqueue_and_set_args(function_name,
diff --git a/pyopencl/scan.py b/pyopencl/scan.py
index 6bea3d324..4c1fc8d19 100644
--- a/pyopencl/scan.py
+++ b/pyopencl/scan.py
@@ -1143,7 +1143,8 @@ def finish_setup(self) -> None:
 
 generic_scan_kernel_cache = WriteOncePersistentDict(
         "pyopencl-generated-scan-kernel-cache-v1",
-        key_builder=_NumpyTypesKeyBuilder())
+        key_builder=_NumpyTypesKeyBuilder(),
+        in_mem_cache_size=0)
 
 
 class GenericScanKernel(GenericScanKernelBase):