diff --git a/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py b/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py
index 94d7ae80ea..69bf081ee3 100644
--- a/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py
+++ b/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py
@@ -45,7 +45,7 @@ ACADOS_SOLVER_TYPE = 'SQP_RTI'
 # much better convergence of the MPC with low iterations
 N = 12
 MAX_T = 10.0
-T_IDXS_LST = [index_function(idx, max_val=MAX_T, max_idx=N+1) for idx in range(N+1)]
+T_IDXS_LST = [index_function(idx, max_val=MAX_T, max_idx=N) for idx in range(N+1)]
 
 T_IDXS = np.array(T_IDXS_LST)
 T_DIFFS = np.diff(T_IDXS, prepend=[0.])
diff --git a/selfdrive/test/process_replay/ref_commit b/selfdrive/test/process_replay/ref_commit
index d81fe18ac1..3226b8614b 100644
--- a/selfdrive/test/process_replay/ref_commit
+++ b/selfdrive/test/process_replay/ref_commit
@@ -1 +1 @@
-c6d7afb13c183852f8d61d5f79495b828ed401ed
\ No newline at end of file
+37aa2e3afedc8364d2bbecc5f1b7ed4efec52e30
\ No newline at end of file