diff --git a/include/evl/mutex.h b/include/evl/mutex.h
index 53b9cafc7cb7fb..b937166b91f9af 100644
--- a/include/evl/mutex.h
+++ b/include/evl/mutex.h
@@ -23,6 +23,7 @@ struct evl_thread;
 #define EVL_MUTEX_PP      	BIT(1)
 #define EVL_MUTEX_CLAIMED	BIT(2)
 #define EVL_MUTEX_CEILING	BIT(3)
+#define EVL_MUTEX_COUNTED	BIT(4)
 
 struct evl_mutex {
 	int wprio;
diff --git a/include/evl/thread.h b/include/evl/thread.h
index 0bf36a6d248832..5c182dd0441412 100644
--- a/include/evl/thread.h
+++ b/include/evl/thread.h
@@ -131,7 +131,7 @@ struct evl_thread {
 		int nr;
 		int active;
 	} poll_context;
-	atomic_t inband_disable_count;
+	atomic_t held_mutex_count;
 	struct irq_work inband_work;
 	struct {
 		struct evl_counter isw;	/* in-band switches */
diff --git a/kernel/evl/mutex.c b/kernel/evl/mutex.c
index ba59debfd986e2..6d11f94ac334e9 100644
--- a/kernel/evl/mutex.c
+++ b/kernel/evl/mutex.c
@@ -53,23 +53,31 @@ static inline int get_ceiling_value(struct evl_mutex *mutex)
 	return clamp(*mutex->ceiling_ref, 1U, (u32)EVL_FIFO_MAX_PRIO);
 }
 
-static inline void disable_inband_switch(struct evl_thread *curr)
+/* mutex->wchan.lock held, irqs off. */
+static inline
+void disable_inband_switch(struct evl_thread *curr, struct evl_mutex *mutex)
 {
 	/*
 	 * Track mutex locking depth: 1) to prevent weak threads from
 	 * being switched back to in-band context on return from OOB
 	 * syscalls, 2) when locking consistency is being checked.
 	 */
-	if (curr->state & (T_WEAK|T_WOLI))
-		atomic_inc(&curr->inband_disable_count);
+	if (unlikely(curr->state & (T_WEAK|T_WOLI))) {
+		atomic_inc(&curr->held_mutex_count);
+		mutex->flags |= EVL_MUTEX_COUNTED;
+	}
 }
 
-static inline void enable_inband_switch(struct evl_thread *curr)
+/* mutex->wchan.lock held, irqs off. */
+static inline
+void enable_inband_switch(struct evl_thread *curr, struct evl_mutex *mutex)
 {
-	if ((curr->state & (T_WEAK|T_WOLI)) &&
-		atomic_dec_return(&curr->inband_disable_count) >= 0) {
-		atomic_set(&curr->inband_disable_count, 0);
-		EVL_WARN_ON_ONCE(CORE, 1);
+	if (unlikely(mutex->flags & EVL_MUTEX_COUNTED)) {
+		mutex->flags &= ~EVL_MUTEX_COUNTED;
+		if (atomic_dec_return(&curr->held_mutex_count) < 0) {
+			atomic_set(&curr->held_mutex_count, 0);
+			EVL_WARN_ON_ONCE(CORE, 1);
+		}
 	}
 }
 
@@ -626,10 +634,9 @@ static int fast_grab_mutex(struct evl_mutex *mutex)
 	 */
 	set_mutex_owner(mutex, curr);
 	raw_spin_unlock(&curr->lock);
+	disable_inband_switch(curr, mutex);
 	raw_spin_unlock_irqrestore(&mutex->wchan.lock, flags);
 
-	disable_inband_switch(curr);
-
 	return 0;
 }
 
@@ -1181,7 +1188,7 @@ int evl_lock_mutex_timeout(struct evl_mutex *mutex, ktime_t timeout,
 			   */
 			if (set_mutex_owner(mutex, curr)) {
 				raw_spin_unlock(&curr->lock);
-				disable_inband_switch(curr);
+				disable_inband_switch(curr, mutex);
 				finish_slow_grab(mutex, currh);
 				raw_spin_unlock(&mutex->wchan.lock);
 				evl_adjust_wait_priority(curr);
@@ -1273,7 +1280,7 @@ int evl_lock_mutex_timeout(struct evl_mutex *mutex, ktime_t timeout,
 	raw_spin_unlock(&curr->rq->lock);
 grab:
 	raw_spin_unlock(&curr->lock);
-	disable_inband_switch(curr);
+	disable_inband_switch(curr, mutex);
 	finish_slow_grab(mutex, currh);
 out:
 	raw_spin_unlock_irqrestore(&mutex->wchan.lock, flags);
@@ -1375,10 +1382,10 @@ void __evl_unlock_mutex(struct evl_mutex *mutex)
 
 	trace_evl_mutex_unlock(mutex);
 
-	enable_inband_switch(curr);
-
 	raw_spin_lock_irqsave(&mutex->wchan.lock, flags);
 
+	enable_inband_switch(curr, mutex);
+
 	/*
 	 * Priority boost for PP mutex is applied to the owner, unlike
 	 * PI boost which is applied to waiters. Therefore, we have to
diff --git a/kernel/evl/syscall.c b/kernel/evl/syscall.c
index be5b92416f57df..f303bc4f822f20 100644
--- a/kernel/evl/syscall.c
+++ b/kernel/evl/syscall.c
@@ -305,7 +305,7 @@ static int do_oob_syscall(struct irq_stage *stage, struct pt_regs *regs,
 		if (signal_pending(tsk) || (curr->info & T_KICKED))
 			prepare_for_signal(tsk, curr, regs);
 		else if ((curr->state & T_WEAK) &&
-			!atomic_read(&curr->inband_disable_count))
+			!atomic_read(&curr->held_mutex_count))
 			evl_switch_inband(EVL_HMDIAG_NONE);
 	}
 
@@ -402,7 +402,7 @@ static int do_inband_syscall(struct pt_regs *regs, unsigned int nr,
 		if (signal_pending(tsk) || (curr->info & T_KICKED))
 			prepare_for_signal(tsk, curr, regs);
 		else if ((curr->state & T_WEAK) &&
-			!atomic_read(&curr->inband_disable_count))
+			!atomic_read(&curr->held_mutex_count))
 			evl_switch_inband(EVL_HMDIAG_NONE);
 	}
 done:
diff --git a/kernel/evl/thread.c b/kernel/evl/thread.c
index 4647a58b93daf7..88f7194324f234 100644
--- a/kernel/evl/thread.c
+++ b/kernel/evl/thread.c
@@ -216,7 +216,7 @@ int evl_init_thread(struct evl_thread *thread,
 	thread->wait_data = NULL;
 	thread->u_window = NULL;
 	thread->observable = iattr->observable;
-	atomic_set(&thread->inband_disable_count, 0);
+	atomic_set(&thread->held_mutex_count, 0);
 	memset(&thread->poll_context, 0, sizeof(thread->poll_context));
 	memset(&thread->stat, 0, sizeof(thread->stat));
 	memset(&thread->altsched, 0, sizeof(thread->altsched));
@@ -1909,7 +1909,7 @@ static void handle_retuser_event(void)
 	evl_schedule();
 
 	if ((curr->state & T_WEAK) &&
-		atomic_read(&curr->inband_disable_count) == 0)
+		atomic_read(&curr->held_mutex_count) == 0)
 		evl_switch_inband(EVL_HMDIAG_NONE);
 }
 
diff --git a/kernel/evl/wait.c b/kernel/evl/wait.c
index c2c161a57c4609..e00307e4a9f268 100644
--- a/kernel/evl/wait.c
+++ b/kernel/evl/wait.c
@@ -87,7 +87,7 @@ void evl_add_wait_queue(struct evl_wait_queue *wq, ktime_t timeout,
 	struct evl_thread *curr = evl_current();
 
 	if ((curr->state & T_WOLI) &&
-		atomic_read(&curr->inband_disable_count) > 0)
+		atomic_read(&curr->held_mutex_count) > 0)
 		evl_notify_thread(curr, EVL_HMDIAG_LKSLEEP, evl_nil);
 
 	__evl_add_wait_queue(curr, wq, timeout, timeout_mode);