diff --git a/examples/dcrlme.ipynb b/examples/dcrlme.ipynb
index eae0e6b3..057ef0c4 100644
--- a/examples/dcrlme.ipynb
+++ b/examples/dcrlme.ipynb
@@ -154,7 +154,7 @@
    "source": [
     "\n",
     "# Init a random key\n",
-    "random_key = jax.random.PRNGKey(seed)\n",
+    "random_key = jax.random.key(seed)\n",
     "\n",
     "# Init environment\n",
     "env = environments.create(env_name, episode_length=episode_length)\n",
diff --git a/qdax/core/neuroevolution/networks/seq2seq_networks.py b/qdax/core/neuroevolution/networks/seq2seq_networks.py
index 476705fa..a4bb2272 100644
--- a/qdax/core/neuroevolution/networks/seq2seq_networks.py
+++ b/qdax/core/neuroevolution/networks/seq2seq_networks.py
@@ -15,9 +15,6 @@
 import numpy as np
 from flax import linen as nn
 
-Array = Any
-PRNGKey = jax.Array
-
 
 class EncoderLSTM(nn.Module):
     """EncoderLSTM Module wrapped in a lifted scan transform."""
@@ -31,14 +28,16 @@ class EncoderLSTM(nn.Module):
     )
     @nn.compact
     def __call__(
-        self, carry: Tuple[Array, Array], x: Array
-    ) -> Tuple[Tuple[Array, Array], Array]:
+        self, carry: Tuple[jax.Array, jax.Array], x: jax.Array
+    ) -> Tuple[Tuple[jax.Array, jax.Array], jax.Array]:
         """Applies the module."""
         lstm_state, is_eos = carry
         features = lstm_state[0].shape[-1]
         new_lstm_state, y = nn.LSTMCell(features)(lstm_state, x)
 
-        def select_carried_state(new_state: Array, old_state: Array) -> Array:
+        def select_carried_state(
+            new_state: jax.Array, old_state: jax.Array
+        ) -> jax.Array:
             return jnp.where(is_eos[:, np.newaxis], old_state, new_state)
 
         # LSTM state is a tuple (c, h).
@@ -49,7 +48,9 @@ def select_carried_state(new_state: Array, old_state: Array) -> Array:
         return (carried_lstm_state, is_eos), y
 
     @staticmethod
-    def initialize_carry(batch_size: int, hidden_size: int) -> Tuple[Array, Array]:
+    def initialize_carry(
+        batch_size: int, hidden_size: int
+    ) -> Tuple[jax.Array, jax.Array]:
         # Use a dummy key since the default state init fn is just zeros.
         return nn.LSTMCell(hidden_size, parent=None).initialize_carry(  # type: ignore
             jax.random.key(0), (batch_size, hidden_size)
@@ -62,7 +63,7 @@ class Encoder(nn.Module):
     hidden_size: int
 
     @nn.compact
-    def __call__(self, inputs: Array) -> Array:
+    def __call__(self, inputs: jax.Array) -> jax.Array:
         batch_size = inputs.shape[0]
         lstm = EncoderLSTM(name="encoder_lstm")
         init_lstm_state = lstm.initialize_carry(batch_size, self.hidden_size)
@@ -95,7 +96,7 @@ class DecoderLSTM(nn.Module):
         split_rngs={"params": False, "lstm": True},
     )
     @nn.compact
-    def __call__(self, carry: Tuple[Array, Array], x: Array) -> Array:
+    def __call__(self, carry: Tuple[jax.Array, jax.Array], x: jax.Array) -> jax.Array:
         """Applies the DecoderLSTM model."""
 
         lstm_state, last_prediction = carry
@@ -124,7 +125,9 @@ class Decoder(nn.Module):
     obs_size: int
 
     @nn.compact
-    def __call__(self, inputs: Array, init_state: Any) -> Tuple[Array, Array]:
+    def __call__(
+        self, inputs: jax.Array, init_state: Any
+    ) -> Tuple[jax.Array, jax.Array]:
         """Applies the decoder model.
 
         Args:
@@ -166,8 +169,8 @@ def setup(self) -> None:
 
     @nn.compact
     def __call__(
-        self, encoder_inputs: Array, decoder_inputs: Array
-    ) -> Tuple[Array, Array]:
+        self, encoder_inputs: jax.Array, decoder_inputs: jax.Array
+    ) -> Tuple[jax.Array, jax.Array]:
         """Applies the seq2seq model.
 
         Args:
@@ -194,7 +197,7 @@ def __call__(
 
         return logits, predictions
 
-    def encode(self, encoder_inputs: Array) -> Array:
+    def encode(self, encoder_inputs: jax.Array) -> jax.Array:
         # encode inputs
         init_decoder_state = self.encoder(encoder_inputs)
         final_output, _hidden_state = init_decoder_state
diff --git a/qdax/utils/train_seq2seq.py b/qdax/utils/train_seq2seq.py
index bd9570a9..fa7825b0 100644
--- a/qdax/utils/train_seq2seq.py
+++ b/qdax/utils/train_seq2seq.py
@@ -19,9 +19,6 @@
 from qdax.custom_types import Params, RNGKey
 from qdax.environments.bd_extractors import AuroraExtraInfoNormalization
 
-Array = Any
-PRNGKey = Any
-
 
 def get_model(
     obs_size: int, teacher_force: bool = False, hidden_size: int = 10
@@ -40,7 +37,7 @@ def get_model(
 
 
 def get_initial_params(
-    model: Seq2seq, random_key: PRNGKey, encoder_input_shape: Tuple[int, ...]
+    model: Seq2seq, random_key: RNGKey, encoder_input_shape: Tuple[int, ...]
 ) -> Dict[str, Any]:
     """
     Returns the initial parameters of a seq2seq model.
@@ -62,8 +59,8 @@ def get_initial_params(
 @jax.jit
 def train_step(
     state: train_state.TrainState,
-    batch: Array,
-    lstm_random_key: PRNGKey,
+    batch: jax.Array,
+    lstm_random_key: RNGKey,
 ) -> Tuple[train_state.TrainState, Dict[str, float]]:
     """
     Trains for one step.
diff --git a/tests/baselines_test/dcrlme_test.py b/tests/baselines_test/dcrlme_test.py
index 05304944..1bc9688d 100644
--- a/tests/baselines_test/dcrlme_test.py
+++ b/tests/baselines_test/dcrlme_test.py
@@ -61,7 +61,7 @@ def test_dcrlme() -> None:
     policy_delay = 2
 
     # Init a random key
-    random_key = jax.random.PRNGKey(seed)
+    random_key = jax.random.key(seed)
 
     # Init environment
     env = environments.create(env_name, episode_length=episode_length)
diff --git a/tests/utils_test/uncertainty_metrics_test.py b/tests/utils_test/uncertainty_metrics_test.py
index d49e2527..3f2caea1 100644
--- a/tests/utils_test/uncertainty_metrics_test.py
+++ b/tests/utils_test/uncertainty_metrics_test.py
@@ -25,7 +25,7 @@ def test_uncertainty_metrics() -> None:
     genotype_dim = 8
 
     # Init a random key
-    random_key = jax.random.PRNGKey(seed)
+    random_key = jax.random.key(seed)
 
     # First, init a deterministic environment
     init_policies = jax.random.uniform(