diff --git a/src/task.c b/src/task.c
index 761fc29..7ce1cd2 100644
--- a/src/task.c
+++ b/src/task.c
@@ -94,16 +94,18 @@
 			 * the task's first thread for the job.
 			 */
 			thr = my_ffsl(t->thread_mask) - 1;
-			if (MT_LIST_ADDQ(&task_per_thread[thr].shared_tasklet_list,
-			                 (struct mt_list *)&((struct tasklet *)t)->list)) {
-				_HA_ATOMIC_ADD(&tasks_run_queue, 1);
-				_HA_ATOMIC_ADD(&task_per_thread[thr].task_list_size, 1);
-				if (sleeping_thread_mask & (1UL << thr)) {
-					_HA_ATOMIC_AND(&sleeping_thread_mask, ~(1UL << thr));
-					wake_thread(thr);
-				}
-				return;
+
+			/* Beware: tasks that have never run don't have their ->list empty yet! */
+			LIST_INIT(&((struct tasklet *)t)->list);
+			BUG_ON(!MT_LIST_ADDQ(&task_per_thread[thr].shared_tasklet_list,
+			                     (struct mt_list *)&((struct tasklet *)t)->list));
+			_HA_ATOMIC_ADD(&tasks_run_queue, 1);
+			_HA_ATOMIC_ADD(&task_per_thread[thr].task_list_size, 1);
+			if (sleeping_thread_mask & (1UL << thr)) {
+				_HA_ATOMIC_AND(&sleeping_thread_mask, ~(1UL << thr));
+				wake_thread(thr);
 			}
+			return;
 		}
 	}
 }