diff --git a/include/haproxy/task-t.h b/include/haproxy/task-t.h
index 75e2968da..45d68a85a 100644
--- a/include/haproxy/task-t.h
+++ b/include/haproxy/task-t.h
@@ -128,6 +128,12 @@ struct notification {
  * pointer if the task/tasklet remains valid, and return NULL if it has been
  * deleted. The scheduler relies on this to know if it should update its state
  * on return.
+ *
+ * Keep in mind that tasks can be cast to tasklets while in the final tasklet
+ * queues, and will be listed via the tasklet's <list> instead of the task's
+ * <rq>. However other fields (wq, common) must remain totally valid for the
+ * task during this time. This explains why certain elements are present in
+ * the common part even though pure tasklets do not need them.
  */
 #define TASK_COMMON							\
 	unsigned int state; /* task state : bitfield of TASK_	*/ \
@@ -138,14 +144,14 @@ struct notification {
 	uint32_t wake_date;              /* date of the last task wakeup */ \
 	unsigned int calls;              /* number of times process was called */ \
 	TASK_DEBUG_STORAGE;					\
-	short last_run;                  /* 16-bit now_ms of last run */
-	/* a 16- or 48-bit hole remains here and is used by task */
+	short last_run;                  /* 16-bit now_ms of last run */          \
+	short nice;                      /* task prio from -1024 to +1024 */      \
+	int expire;                      /* next expiration date for this task, in ticks */
+	/* total: 36 or 48 bytes on 32/64 bit platforms */
 
 /* The base for all tasks */
 struct task {
 	TASK_COMMON;			/* must be at the beginning! */
-	short nice;                     /* task prio from -1024 to +1024 */
-	int expire;			/* next expiration date for this task, in ticks */
 	struct eb32_node rq;		/* ebtree node used to hold the task in the run queue */
 	/* WARNING: the struct task is often aliased as a struct tasklet when
 	 * it is NOT in the run queue. The tasklet has its struct list here
@@ -158,7 +164,6 @@ struct task {
 /* lightweight tasks, without priority, mainly used for I/Os */
 struct tasklet {
 	TASK_COMMON;			/* must be at the beginning! */
-	/* 48-bit hole here */
 	struct list list;
 	/* WARNING: the struct task is often aliased as a struct tasklet when
 	 * it is not in the run queue. The task has its struct rq here where