diff --git a/sys/kern/kern_intr.c b/sys/kern/kern_intr.c
--- a/sys/kern/kern_intr.c
+++ b/sys/kern/kern_intr.c
@@ -205,7 +205,7 @@
 	sched_clear_tdname(td);
 #endif
 	thread_lock(td);
-	sched_prio(td, pri);
+	sched_ithread_prio(td, pri);
 	thread_unlock(td);
 }
 
diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -391,7 +391,7 @@
 		cc->cc_thread = td;
 		thread_lock(td);
 		sched_class(td, PRI_ITHD);
-		sched_prio(td, PI_SOFTCLOCK);
+		sched_ithread_prio(td, PI_SOFTCLOCK);
 		TD_SET_IWAIT(td);
 		thread_lock_set(td, (struct mtx *)&cc->cc_lock);
 		thread_unlock(td);
diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c
--- a/sys/kern/sched_4bsd.c
+++ b/sys/kern/sched_4bsd.c
@@ -924,6 +924,15 @@
 		turnstile_adjust(td, oldprio);
 }
 
+void
+sched_ithread_prio(struct thread *td, u_char prio)
+{
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	MPASS(td->td_pri_class == PRI_ITHD);
+	td->td_base_ithread_pri = prio;
+	sched_prio(td, prio);
+}
+
 void
 sched_user_prio(struct thread *td, u_char prio)
 {
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -1962,6 +1962,18 @@
 		turnstile_adjust(td, oldprio);
 }
 
+/*
+ * Set the base interrupt thread priority.
+ */
+void
+sched_ithread_prio(struct thread *td, u_char prio)
+{
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	MPASS(td->td_pri_class == PRI_ITHD);
+	td->td_base_ithread_pri = prio;
+	sched_prio(td, prio);
+}
+
 /*
  * Set the base user priority, does not effect current running priority.
  */
diff --git a/sys/kern/subr_busdma_bounce.c b/sys/kern/subr_busdma_bounce.c
--- a/sys/kern/subr_busdma_bounce.c
+++ b/sys/kern/subr_busdma_bounce.c
@@ -439,7 +439,7 @@
 
 	thread_lock(curthread);
 	sched_class(curthread, PRI_ITHD);
-	sched_prio(curthread, PI_SWI(SWI_BUSDMA));
+	sched_ithread_prio(curthread, PI_SWI(SWI_BUSDMA));
 	thread_unlock(curthread);
 	for (;;) {
 		mtx_lock(&bounce_lock);
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -257,6 +257,7 @@
 #define	td_siglist	td_sigqueue.sq_signals
 	u_char		td_lend_user_pri; /* (t) Lend user pri. */
 	u_char		td_allocdomain;	/* (b) NUMA domain backing this struct thread. */
+	u_char		td_base_ithread_pri; /* (t) Base ithread pri */
 	struct kmsan_td	*td_kmsan;	/* (k) KMSAN state */
 
 /* Cleared during fork1() */
diff --git a/sys/sys/sched.h b/sys/sys/sched.h
--- a/sys/sys/sched.h
+++ b/sys/sys/sched.h
@@ -95,6 +95,7 @@
 void	sched_exit_thread(struct thread *td, struct thread *child);
 u_int	sched_estcpu(struct thread *td);
 void	sched_fork_thread(struct thread *td, struct thread *child);
+void	sched_ithread_prio(struct thread *td, u_char prio);
 void	sched_lend_prio(struct thread *td, u_char prio);
 void	sched_lend_user_prio(struct thread *td, u_char pri);
 void	sched_lend_user_prio_cond(struct thread *td, u_char pri);