diff --git a/brainunit/math/_compat_numpy.py b/brainunit/math/_compat_numpy.py
index 5291ef9..16aa807 100644
--- a/brainunit/math/_compat_numpy.py
+++ b/brainunit/math/_compat_numpy.py
@@ -1168,7 +1168,7 @@ def intersect1d(
     ar2: Union[jax.Array, np.ndarray],
     assume_unique: bool = False,
     return_indices: bool = False
-) -> Union[jax.Array, Quantity, tuple[jax.Array | Quantity, jax.Array, jax.Array]]:
+) -> Union[jax.Array, Quantity, tuple[Union[jax.Array, Quantity], jax.Array, jax.Array]]:
   fail_for_dimension_mismatch(ar1, ar2, 'intersect1d')
   unit = None
   if isinstance(ar1, Quantity):