diff --git a/gpax/models/spm.py b/gpax/models/spm.py
index d7d08da..6ace03a 100644
--- a/gpax/models/spm.py
+++ b/gpax/models/spm.py
@@ -103,6 +103,7 @@ def fit(self, rng_key: jnp.array, X: jnp.ndarray, y: jnp.ndarray,
                 optionally specify a cpu or gpu device on which to run the inference;
                 e.g., ``device=jax.devices("cpu")[0]`` 
         """
+        X, y = self._set_data(X, y)
         if device:
             X = jax.device_put(X, device)
             y = jax.device_put(y, device)
@@ -165,6 +166,7 @@ def predict(self, rng_key: jnp.ndarray, X_new: jnp.ndarray,
         Returns:
             Point predictions (or their mean) and posterior predictive distribution
         """
+        X_new = self._set_data(X_new)
         if samples is None:
             samples = self.get_samples(chain_dim=False)
         if device:
@@ -183,3 +185,10 @@ def predict(self, rng_key: jnp.ndarray, X_new: jnp.ndarray,
 
     def _print_summary(self):
         self.mcmc.print_summary()
+
+    def _set_data(self,
+                  X: jnp.ndarray, y: Optional[jnp.ndarray] = None,
+                  ) -> Tuple[jnp.ndarray]:
+        if y is not None:
+            return X, y
+        return X