Fix for windows

qutip/qobj.py

@@ -333,10 +333,15 @@ def __init__(self, inpt=None, dims=None, shape=None,
         # use cases such as enr_fock and other enr_ functions.
         # This does leave open the possibility of data still being
         # misused such as Qobj(complex[n**2][1], dims = [[n],[n]])
-        if (self._data.shape[0] > np.prod(flatten(self.dims[0])) or
-           self._data.shape[1] > np.prod(flatten(self.dims[1]))) and \
-           self.type != 'super':
-
+        dims_size = (
+            np.prod(flatten(self.dims[0]), dtype=np.int64),
+            np.prod(flatten(self.dims[1]), dtype=np.int64)
+        )
+        shape = self._data.shape
+        if (
+            (shape[0] > dims_size[0] or shape[1] > dims_size[1])
+            and self.type != 'super'
+        ):
             raise ValueError(f"Qobj has smaller dims {self.dims} " +
                              f"than underlying shape {self._data.shape}")