diff --git a/grgrjax/helpers.py b/grgrjax/helpers.py
index 1cc2169..3867b18 100644
--- a/grgrjax/helpers.py
+++ b/grgrjax/helpers.py
@@ -4,7 +4,7 @@
 import time
 import jax.numpy as jnp
 from jax._src.api import (_check_input_dtype_jacfwd, _check_input_dtype_jacrev, _check_output_dtype_jacfwd, _check_output_dtype_jacrev, _ensure_index, _jvp,
-                          _vjp, _std_basis, _jacfwd_unravel, _jacrev_unravel, lu, argnums_partial, tree_map, tree_structure, tree_transpose, partial, Callable, Sequence, Union, vmap)
+                          _vjp, _std_basis, _jacfwd_unravel, _jacrev_unravel, lu, argnums_partial, tree_map, tree_structure, tree_transpose, partial, Callable, Sequence, vmap)
 # fix import location for jax 0.4.1
 try:
     from jax._src.api import _check_callable
@@ -23,7 +23,7 @@ def amax(x, return_arg=False):
         return absx.max()
 
 
-def jvp_vmap(fun: Callable, argnums: Union[int, Sequence[int]] = 0):
+def jvp_vmap(fun: Callable, argnums: int | Sequence[int] = 0):
     """Vectorized (forward-mode) jacobian-vector product of ``fun``. This is by large adopted from the implementation of jacfwd in jax._src.api.
 
     Args:
@@ -49,7 +49,7 @@ def jvpfun(args, tangents, **kwargs):
     return jvpfun
 
 
-def vjp_vmap(fun: Callable, argnums: Union[int, Sequence[int]] = 0):
+def vjp_vmap(fun: Callable, argnums: int | Sequence[int] = 0):
     """Vectorized (reverse-mode) vector-jacobian product of ``fun``. This is by large adopted from the implementation of jacrev in jax._src.api.
 
     Args:
@@ -74,7 +74,7 @@ def vjpfun(args, tangents, **kwargs):
     return vjpfun
 
 
-def val_and_jacfwd(fun: Callable, argnums: Union[int, Sequence[int]] = 0,
+def val_and_jacfwd(fun: Callable, argnums: int | Sequence[int] = 0,
                    has_aux: bool = False, holomorphic: bool = False) -> Callable:
     """Value and Jacobian of ``fun`` evaluated column-by-column using forward-mode AD. Apart from returning the function value, this is one-to-one adopted from jax._src.api.
 
@@ -122,7 +122,7 @@ def jacfun(*args, **kwargs):
     return jacfun
 
 
-def val_and_jacrev(fun: Callable, argnums: Union[int, Sequence[int]] = 0,
+def val_and_jacrev(fun: Callable, argnums: int | Sequence[int] = 0,
                    has_aux: bool = False, holomorphic: bool = False, allow_int: bool = False) -> Callable:
     """Value and Jacobian of ``fun`` evaluated row-by-row using reverse-mode AD. Apart from returning the function value, this is one-to-one adopted from jax._src.api.