diff --git a/jpc/_test.py b/jpc/_test.py
index 83c1096..54a295d 100644
--- a/jpc/_test.py
+++ b/jpc/_test.py
@@ -128,7 +128,7 @@ def test_hpc(
           atol=1e-3
       ),
       dt: Union[float, int] = None
-):
+) -> Tuple[Scalar, Scalar, Scalar, Array]:
     """Computes test metrics for hybrid predictive coding.
 
     Calculates input accuracy of (i) amortiser, (ii) generative, and (ii)
@@ -171,7 +171,7 @@ def test_hpc(
     amort_preds = amort_activities[0]
     hpc_preds = solve_pc_activities(
         network=generator,
-        activities=amort_activities[1:],
+        activities=amort_activities,
         output=output,
         solver=solver,
         n_iters=n_iters,