diff --git a/gpax/models/bnn.py b/gpax/models/bnn.py
index 2ff2eef..ffd0954 100644
--- a/gpax/models/bnn.py
+++ b/gpax/models/bnn.py
@@ -52,7 +52,7 @@ def sample_biases(name: str, channels: int) -> jnp.ndarray:
     return b
 
 
-def get_mlp(architecture: List[int]) -> Callable:
+def get_mlp(architecture: List[int]) -> Callable[[jnp.ndarray, Dict[str, jnp.ndarray]], jnp.ndarray]:
     """Returns a function that represents an MLP for a given architecture."""
     def mlp(X: jnp.ndarray, params: Dict[str, jnp.ndarray]) -> jnp.ndarray:
         """MLP for a single MCMC sample of weights and biases, handling arbitrary number of layers."""
@@ -65,7 +65,7 @@ def mlp(X: jnp.ndarray, params: Dict[str, jnp.ndarray]) -> jnp.ndarray:
     return mlp
 
 
-def get_mlp_prior(input_dim: int, output_dim: int, architecture: List[int]) -> Dict[str, jnp.ndarray]:
+def get_mlp_prior(input_dim: int, output_dim: int, architecture: List[int]) -> Callable[[], Dict[str, jnp.ndarray]]:
     """Priors over weights and biases for a Bayesian MLP"""
     def mlp_prior():
         params = {}
diff --git a/gpax/models/dkl.py b/gpax/models/dkl.py
index ad7a022..689af97 100644
--- a/gpax/models/dkl.py
+++ b/gpax/models/dkl.py
@@ -164,7 +164,7 @@ def sample_biases(name: str, channels: int) -> jnp.ndarray:
     return b
 
 
-def get_mlp(architecture: List[int]) -> Callable:
+def get_mlp(architecture: List[int]) -> Callable[[jnp.ndarray, Dict[str, jnp.ndarray]], jnp.ndarray]:
     """Returns a function that represents an MLP for a given architecture."""
     def mlp(X: jnp.ndarray, params: Dict[str, jnp.ndarray]) -> jnp.ndarray:
         """MLP for a single MCMC sample of weights and biases, handling arbitrary number of layers."""
@@ -177,7 +177,7 @@ def mlp(X: jnp.ndarray, params: Dict[str, jnp.ndarray]) -> jnp.ndarray:
     return mlp
 
 
-def get_mlp_prior(input_dim: int, output_dim: int, architecture: List[int]) -> Dict[str, jnp.ndarray]:
+def get_mlp_prior(input_dim: int, output_dim: int, architecture: List[int]) -> Callable[[], Dict[str, jnp.ndarray]]:
     """Priors over weights and biases for a Bayesian MLP"""
     def mlp_prior():
         params = {}
@@ -190,4 +190,4 @@ def mlp_prior():
         params[f"w{len(architecture)}"] = sample_weights(f"w{len(architecture)}", in_channels, output_dim)
         params[f"b{len(architecture)}"] = sample_biases(f"b{len(architecture)}", output_dim)
         return params
-    return mlp_prior
+    return mlp_prior
\ No newline at end of file