diff --git a/src/toast/ops/sim_ground_utils.py b/src/toast/ops/sim_ground_utils.py
index a86e61d97..0ea2bb187 100644
--- a/src/toast/ops/sim_ground_utils.py
+++ b/src/toast/ops/sim_ground_utils.py
@@ -258,6 +258,7 @@ def oscillate_el(
                 "Cannot perform {:.2f} deg elevation oscillation in {:.2f} s "
                 "with {:.2f} deg/s^2 acceleration".format(
                     np.degrees(el_mod_amplitude * 2),
+                    t_mod,
                     np.degrees(el_accel),
                 )
             )