diff --git a/mlir/python/mlir/runtime/np_to_memref.py b/mlir/python/mlir/runtime/np_to_memref.py
--- a/mlir/python/mlir/runtime/np_to_memref.py
+++ b/mlir/python/mlir/runtime/np_to_memref.py
@@ -23,13 +23,14 @@
   _fields_ = [("f16", ctypes.c_int16)]
 
 
+# https://stackoverflow.com/questions/26921836/correct-way-to-test-for-numpy-dtype
 def as_ctype(dtp):
   """Converts dtype to ctype."""
-  if dtp is np.dtype(np.complex128):
+  if dtp == np.dtype(np.complex128):
     return C128
-  if dtp is np.dtype(np.complex64):
+  if dtp == np.dtype(np.complex64):
     return C64
-  if dtp is np.dtype(np.float16):
+  if dtp == np.dtype(np.float16):
     return F16
   return np.ctypeslib.as_ctypes_type(dtp)