diff --git a/frc971/control_loops/aiming/aiming.cc b/frc971/control_loops/aiming/aiming.cc
index 4cf9255..572ed1c 100644
--- a/frc971/control_loops/aiming/aiming.cc
+++ b/frc971/control_loops/aiming/aiming.cc
@@ -54,6 +54,8 @@
 }  // namespace
 
 TurretGoal AimerGoal(const ShotConfig &config, const RobotState &state) {
+  CHECK(config.ball_speed_over_ground > 0.0)
+      << ": Ball speed must be positive.";
   TurretGoal result;
   // This code manages compensating the goal turret heading for the robot's
   // current velocity, to allow for shooting on-the-fly.
diff --git a/frc971/control_loops/aiming/aiming_test.cc b/frc971/control_loops/aiming/aiming_test.cc
index 4ec7eb9..a4f7bf2 100644
--- a/frc971/control_loops/aiming/aiming_test.cc
+++ b/frc971/control_loops/aiming/aiming_test.cc
@@ -158,4 +158,17 @@
   EXPECT_FLOAT_EQ(0.0, goal.velocity);
 }
 
+// Tests that we fail if the ballspeed is zero.  Can't hit anything if the ball
+// isn't moving.
+TEST(AimerDeathTest, ZeroBallSpeed) {
+  const Pose target({0.0, 0.0, 0.0}, 0.0);
+  Pose robot_pose({1.0, 1.0, 1.0}, 0.0);
+  const constants::Range range{-2.36, 2.36, -2.16, 2.16};
+  const double kBallSpeed = 0.0;
+  EXPECT_DEATH(AimerGoal(ShotConfig{target, ShotMode::kShootOnTheFly, range,
+                                    kBallSpeed, 0.0, 0.0},
+                         RobotState{robot_pose, {0.0, 0.0}, 0.0, 0.0}),
+               "Ball speed must be positive.");
+}
+
 }  // namespace frc971::control_loops::aiming::testing