diff --git a/optax/_src/alias.py b/optax/_src/alias.py
index ac2ff572d..88812738a 100644
--- a/optax/_src/alias.py
+++ b/optax/_src/alias.py
@@ -39,6 +39,8 @@ def adabelief(
     b2: jax.typing.ArrayLike = 0.999,
     eps: jax.typing.ArrayLike = 1e-16,
     eps_root: jax.typing.ArrayLike = 1e-16,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
     *,
     nesterov: bool = False,
 ) -> base.GradientTransformationExtraArgs:
@@ -136,6 +138,7 @@ def adabelief(
           eps_root=eps_root,
           nesterov=nesterov,
       ),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -330,6 +333,8 @@ def adagrad(
     learning_rate: base.ScalarOrSchedule,
     initial_accumulator_value: jax.typing.ArrayLike = 0.1,
     eps: jax.typing.ArrayLike = 1e-7,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""The Adagrad optimizer.
 
@@ -407,6 +412,7 @@ def adagrad(
       transform.scale_by_rss(
           initial_accumulator_value=initial_accumulator_value, eps=eps
       ),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -603,7 +609,7 @@ def adamw(
     eps_root: jax.typing.ArrayLike = 0.0,
     mu_dtype: Optional[Any] = None,
     weight_decay: base.ScalarOrSchedule = 1e-4,
-    mask: Optional[Union[Any, Callable[[base.Params], Any]]] = None,
+    weight_decay_mask: MaskOrFn = None,
     *,
     nesterov: bool = False,
 ) -> base.GradientTransformationExtraArgs:
@@ -722,7 +728,7 @@ def adamw(
           mu_dtype=mu_dtype,
           nesterov=nesterov,
       ),
-      transform.add_decayed_weights(weight_decay, mask),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -814,7 +820,7 @@ def adan(
     eps: jax.typing.ArrayLike = 1e-8,
     eps_root: jax.typing.ArrayLike = 1e-8,
     weight_decay: base.ScalarOrSchedule = 0.0,
-    mask: Optional[Union[Any, Callable[[base.Params], Any]]] = None,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""The ADAptive Nesterov momentum algorithm (Adan).
 
@@ -919,7 +925,7 @@ def adan(
           eps=eps,
           eps_root=eps_root,
       ),
-      transform.add_decayed_weights(weight_decay, mask),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -930,7 +936,7 @@ def lion(
     b2: jax.typing.ArrayLike = 0.99,
     mu_dtype: Optional[Any] = None,
     weight_decay: base.ScalarOrSchedule = 1e-3,
-    mask: Optional[Union[Any, Callable[[base.Params], Any]]] = None,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""The Lion optimizer.
 
@@ -1015,7 +1021,7 @@ def lion(
   """
   return combine.chain(
       transform.scale_by_lion(b1=b1, b2=b2, mu_dtype=mu_dtype),
-      transform.add_decayed_weights(weight_decay, mask),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -1029,6 +1035,8 @@ def amsgrad(
     mu_dtype: Optional[Any] = None,
     bias_correction_mu: bool = True,
     bias_correction_nu: bool = True,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   """The AMSGrad optimizer.
 
@@ -1091,6 +1099,7 @@ def amsgrad(
           bias_correction_mu=bias_correction_mu,
           bias_correction_nu=bias_correction_nu,
       ),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -1238,7 +1247,7 @@ def lamb(
     eps: jax.typing.ArrayLike = 1e-6,
     eps_root: jax.typing.ArrayLike = 0.0,
     weight_decay: base.ScalarOrSchedule = 0.0,
-    mask: MaskOrFn = None,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   """The LAMB optimizer.
 
@@ -1294,7 +1303,7 @@ def lamb(
   """
   return combine.chain(
       transform.scale_by_adam(b1=b1, b2=b2, eps=eps, eps_root=eps_root),
-      transform.add_decayed_weights(weight_decay=weight_decay, mask=mask),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_trust_ratio(),
       transform.scale_by_learning_rate(learning_rate),
   )
@@ -1552,6 +1561,8 @@ def optimistic_gradient_descent(
     learning_rate: base.ScalarOrSchedule,
     alpha: base.ScalarOrSchedule = 1.0,
     beta: base.ScalarOrSchedule = 1.0,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""An Optimistic Gradient Descent optimizer.
 
@@ -1611,6 +1622,7 @@ def optimistic_gradient_descent(
   """
   return combine.chain(
       transform.scale_by_optimistic_gradient(alpha=alpha, beta=beta),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -1623,6 +1635,8 @@ def optimistic_adam(
     eps: jax.typing.ArrayLike = 1e-08,
     eps_root: jax.typing.ArrayLike = 0.0,
     mu_dtype: Optional[Any] = None,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
     *,
     nesterov: bool = True,
 ) -> base.GradientTransformationExtraArgs:
@@ -1735,12 +1749,15 @@ def optimistic_adam(
       ),
       transform.scale_by_optimistic_gradient(alpha=learning_rate,
                                              beta=optimism),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(1.0),  # flips the sign
   )
 
 
 def optimistic_adam_v2(
     learning_rate: base.ScalarOrSchedule,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
     *,
     alpha: jax.typing.ArrayLike = 1.0,
     beta: jax.typing.ArrayLike = 1.0,
@@ -1857,6 +1874,7 @@ def optimistic_adam_v2(
           nesterov=nesterov,
       ),
       transform.scale_by_optimistic_gradient(alpha=alpha, beta=beta),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -1868,6 +1886,8 @@ def radam(
     eps: jax.typing.ArrayLike = 1e-8,
     eps_root: jax.typing.ArrayLike = 0.0,
     threshold: jax.typing.ArrayLike = 5.0,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
     *,
     nesterov: bool = False,
 ) -> base.GradientTransformationExtraArgs:
@@ -1928,6 +1948,7 @@ def radam(
           threshold=threshold,
           nesterov=nesterov,
       ),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -1942,6 +1963,8 @@ def rmsprop(
     momentum: Optional[jax.typing.ArrayLike] = None,
     nesterov: bool = False,
     bias_correction: bool = False,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""A flexible RMSProp optimizer.
 
@@ -2022,6 +2045,7 @@ def rmsprop(
             eps_in_sqrt=eps_in_sqrt,
             bias_correction=bias_correction,
         ),
+        transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
         transform.scale_by_learning_rate(learning_rate),
         (
             transform.trace(decay=momentum, nesterov=nesterov)
@@ -2051,6 +2075,8 @@ def sgd(
     momentum: Optional[jax.typing.ArrayLike] = None,
     nesterov: bool = False,
     accumulator_dtype: Optional[Any] = None,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""A canonical Stochastic Gradient Descent optimizer.
 
@@ -2132,12 +2158,16 @@ def sgd(
     opt = base.identity()
   return combine.chain(
       opt,
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
 
 def sm3(
     learning_rate: jax.typing.ArrayLike, momentum: jax.typing.ArrayLike = 0.9
+,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   r"""The SM3 optimizer.
 
@@ -2242,6 +2272,7 @@ def sm3(
   """
   return combine.chain(
       transform.scale_by_sm3(momentum),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale(-learning_rate),
   )
 
@@ -2251,6 +2282,8 @@ def yogi(
     b1: jax.typing.ArrayLike = 0.9,
     b2: jax.typing.ArrayLike = 0.999,
     eps: jax.typing.ArrayLike = 1e-3,
+    weight_decay: base.ScalarOrSchedule = 0.0,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   # pylint: disable=line-too-long
   """The Yogi optimizer.
@@ -2301,6 +2334,7 @@ def yogi(
   # pylint: enable=line-too-long
   return combine.chain(
       transform.scale_by_yogi(b1=b1, b2=b2, eps=eps),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
@@ -2396,7 +2430,7 @@ def adamaxw(
     b2: jax.typing.ArrayLike = 0.999,
     eps: jax.typing.ArrayLike = 1e-8,
     weight_decay: base.ScalarOrSchedule = 1e-4,
-    mask: Optional[Union[Any, Callable[[base.Params], Any]]] = None,
+    weight_decay_mask: MaskOrFn = None,
 ) -> base.GradientTransformationExtraArgs:
   """Adamax with weight decay regularization.
 
@@ -2460,7 +2494,7 @@ def adamaxw(
   """
   return combine.chain(
       transform.scale_by_adamax(b1=b1, b2=b2, eps=eps),
-      transform.add_decayed_weights(weight_decay, mask),
+      transform.add_decayed_weights(weight_decay, mask=weight_decay_mask),
       transform.scale_by_learning_rate(learning_rate),
   )
 
diff --git a/optax/transforms/_adding.py b/optax/transforms/_adding.py
index 5e894cccb..903364d3d 100644
--- a/optax/transforms/_adding.py
+++ b/optax/transforms/_adding.py
@@ -57,8 +57,6 @@ def init_fn(params):
       return base.EmptyState()
 
   def update_fn(updates, state, params):
-    if params is None:
-      raise ValueError(base.NO_PARAMS_MSG)
     if callable(weight_decay):
       new_state = WeightDecaySchedule(numerics.safe_increment(state.count))
     else:
@@ -68,6 +66,9 @@ def update_fn(updates, state, params):
     if isinstance(weight_decay, (int, float)) and weight_decay == 0.0:
       return updates, new_state
 
+    if params is None:
+      raise ValueError(base.NO_PARAMS_MSG)
+
     s = weight_decay(state.count) if callable(weight_decay) else weight_decay
     updates = jax.tree.map(
         lambda g, p: None if g is None else g + s * p,
diff --git a/optax/tree_utils/_state_utils.py b/optax/tree_utils/_state_utils.py
index 2028805c8..b622a0237 100644
--- a/optax/tree_utils/_state_utils.py
+++ b/optax/tree_utils/_state_utils.py
@@ -437,13 +437,13 @@ def tree_set(
       ...  )
       >>> state = opt.init(params)
       >>> print(state)
-      InjectStatefulHyperparamsState(count=Array(0, dtype=int32), hyperparams={'learning_rate': Array(1., dtype=float32)}, hyperparams_states={'learning_rate': WrappedScheduleState(count=Array(0, dtype=int32))}, inner_state=(EmptyState(), EmptyState()))
+      InjectStatefulHyperparamsState(count=Array(0, dtype=int32), hyperparams={'weight_decay': Array(0., dtype=float32), 'learning_rate': Array(1., dtype=float32)}, hyperparams_states={'learning_rate': WrappedScheduleState(count=Array(0, dtype=int32))}, inner_state=(EmptyState(), EmptyState(), EmptyState()))
       >>> filtering = lambda path, value: isinstance(value, jnp.ndarray)
       >>> new_state = optax.tree_utils.tree_set(
       ...   state, filtering, learning_rate=jnp.asarray(0.1)
       ... )
       >>> print(new_state)
-      InjectStatefulHyperparamsState(count=Array(0, dtype=int32), hyperparams={'learning_rate': Array(0.1, dtype=float32, weak_type=True)}, hyperparams_states={'learning_rate': WrappedScheduleState(count=Array(0, dtype=int32))}, inner_state=(EmptyState(), EmptyState()))
+      InjectStatefulHyperparamsState(count=Array(0, dtype=int32), hyperparams={'weight_decay': Array(0., dtype=float32), 'learning_rate': Array(0.1, dtype=float32, weak_type=True)}, hyperparams_states={'learning_rate': WrappedScheduleState(count=Array(0, dtype=int32))}, inner_state=(EmptyState(), EmptyState(), EmptyState()))
 
   .. note:: The recommended usage to inject hyperparameters schedules is through
     :func:`optax.inject_hyperparams`. This function is a helper for other
diff --git a/optax/tree_utils/_state_utils_test.py b/optax/tree_utils/_state_utils_test.py
index a55884d91..0c5676d32 100644
--- a/optax/tree_utils/_state_utils_test.py
+++ b/optax/tree_utils/_state_utils_test.py
@@ -195,6 +195,7 @@ def test_map_params_to_none(self):
         (
             transform.ScaleByRssState(sum_of_squares={'a': None}),
             base.EmptyState(),
+            base.EmptyState(),
         ),
     )
 
@@ -378,7 +379,7 @@ def get_learning_rate(state):
 
       for i in range(4):
         # we simply update state, we don't care about updates.
-        _, state = opt.update(params, state)
+        _, state = opt.update(params, state, params)
         lr = get_learning_rate(state)
         self.assertEqual(lr, 1 / (i + 1))
 
@@ -465,7 +466,7 @@ def set_learning_rate(state, lr):
       for i in range(4):
         modified_state = set_learning_rate(modified_state, lr / (i + 1))
         # we simply update state, we don't care about updates.
-        _, modified_state = opt.update(params, modified_state)
+        _, modified_state = opt.update(params, modified_state, params)
         modified_lr = _state_utils.tree_get(modified_state, 'learning_rate')
         self.assertEqual(modified_lr, lr / (i + 1))