diff --git a/src/adam/parametric/jax/computations_parametric.py b/src/adam/parametric/jax/computations_parametric.py
index f078cd7d..fb0823c9 100644
--- a/src/adam/parametric/jax/computations_parametric.py
+++ b/src/adam/parametric/jax/computations_parametric.py
@@ -66,7 +66,7 @@ def mass_matrix(
             densities (jnp.array): The densities of the parametrized links
 
         Returns:
-            M (jax): Mass Matrix
+            M (jnp.array): Mass Matrix
         """
 
         factory = URDFParametricModelFactory(