diff --git a/loopy/target/pyopencl_execution.py b/loopy/target/pyopencl_execution.py
index f7400d5d04085ca60c1dcfa47c01f9c8fb56a3ea..2da25ba39ceef38a4af105913973226bd3773729 100644
--- a/loopy/target/pyopencl_execution.py
+++ b/loopy/target/pyopencl_execution.py
@@ -688,7 +688,7 @@ class PyOpenCLKernelExecutor(KernelExecutorBase):
 
     def get_code(self, arg_to_dtype=None):
         def process_dtype(dtype):
-            if issubclass(dtype, np.generic):
+            if isinstance(dtype, type) and issubclass(dtype, np.generic):
                 dtype = np.dtype(dtype)
             if isinstance(dtype, np.dtype):
                 dtype = NumpyType(dtype, self.kernel.target)