diff --git a/src/jaxsim/api/references.py b/src/jaxsim/api/references.py
index ae4da7c53..6f20857ef 100644
--- a/src/jaxsim/api/references.py
+++ b/src/jaxsim/api/references.py
@@ -535,7 +535,11 @@ def convert_to_link_force(
 
             return F_X_L @ W_f_F
 
-        W_f_L = jax.vmap(convert_to_link_force)(W_f_F, W_H_Fi, parent_link_idxs)
+        W_f_L_i = jax.vmap(convert_to_link_force)(W_f_F, W_H_Fi, parent_link_idxs)
+
+        # Sum the forces on the parent links.
+        mask = parent_link_idxs[:, jnp.newaxis] == jnp.arange(model.number_of_links())
+        W_f_L = mask.T @ W_f_L_i
 
         return self.apply_link_forces(
             model=model,