diff --git a/include/spdk/thread.h b/include/spdk/thread.h
index deea20c30..c78ae7547 100644
--- a/include/spdk/thread.h
+++ b/include/spdk/thread.h
@@ -224,13 +224,14 @@ void spdk_set_thread(struct spdk_thread *thread);
  * Mark the thread as exited, failing all future spdk_thread_poll() calls. May
  * only be called within an spdk poller or message.
  *
+ * All I/O channel references associated with the thread must be released using
+ * spdk_put_io_channel() prior to calling this function.
  *
  * \param thread The thread to destroy.
  *
- * All I/O channel references associated with the thread must be released using
- * spdk_put_io_channel() prior to calling this function.
+ * \return 0 on success, negated errno on failure.
  */
-void spdk_thread_exit(struct spdk_thread *thread);
+int spdk_thread_exit(struct spdk_thread *thread);
 
 /**
  * Returns whether the thread is marked as exited.
diff --git a/lib/event/reactor.c b/lib/event/reactor.c
index d848e65c9..e89f647b4 100644
--- a/lib/event/reactor.c
+++ b/lib/event/reactor.c
@@ -312,6 +312,7 @@ _spdk_reactor_run(void *arg)
 	struct spdk_lw_thread	*lw_thread, *tmp;
 	char			thread_name[32];
 	uint64_t		rusage_period = 0;
+	int			rc __attribute__((unused));
 
 	SPDK_NOTICELOG("Reactor started on core %u\n", reactor->lcore);
 
@@ -353,7 +354,10 @@ _spdk_reactor_run(void *arg)
 		thread = spdk_thread_get_from_ctx(lw_thread);
 		TAILQ_REMOVE(&reactor->threads, lw_thread, link);
 		spdk_set_thread(thread);
-		spdk_thread_exit(thread);
+		if (!spdk_thread_is_exited(thread)) {
+			rc = spdk_thread_exit(thread);
+			assert(rc == 0);
+		}
 		spdk_thread_destroy(thread);
 	}
 
diff --git a/lib/thread/thread.c b/lib/thread/thread.c
index 71c483154..69d96844c 100644
--- a/lib/thread/thread.c
+++ b/lib/thread/thread.c
@@ -345,14 +345,21 @@ spdk_set_thread(struct spdk_thread *thread)
 	tls_thread = thread;
 }
 
-void
+int
 spdk_thread_exit(struct spdk_thread *thread)
 {
 	SPDK_DEBUGLOG(SPDK_LOG_THREAD, "Exit thread %s\n", thread->name);
 
 	assert(tls_thread == thread);
 
+	if (thread->exit) {
+		SPDK_ERRLOG("thread %s is already marked as exited\n",
+			    thread->name);
+		return -EINVAL;
+	}
+
 	thread->exit = true;
+	return 0;
 }
 
 bool
diff --git a/test/common/lib/ut_multithread.c b/test/common/lib/ut_multithread.c
index 48bd31379..143fdd32e 100644
--- a/test/common/lib/ut_multithread.c
+++ b/test/common/lib/ut_multithread.c
@@ -102,10 +102,14 @@ void
 free_threads(void)
 {
 	uint32_t i;
+	int rc __attribute__((unused));
 
 	for (i = 0; i < g_ut_num_threads; i++) {
 		set_thread(i);
-		spdk_thread_exit(g_ut_threads[i].thread);
+		if (!spdk_thread_is_exited(g_ut_threads[i].thread)) {
+			rc = spdk_thread_exit(g_ut_threads[i].thread);
+			assert(rc == 0);
+		}
 		spdk_thread_destroy(g_ut_threads[i].thread);
 		g_ut_threads[i].thread = NULL;
 	}
diff --git a/test/unit/lib/thread/thread.c/thread_ut.c b/test/unit/lib/thread/thread.c/thread_ut.c
index c3b5d19d3..681ec4230 100644
--- a/test/unit/lib/thread/thread.c/thread_ut.c
+++ b/test/unit/lib/thread/thread.c/thread_ut.c
@@ -754,7 +754,7 @@ thread_exit(void)
 	bool done1 = false, done2 = false;
 	int rc __attribute__((unused));
 
-	allocate_threads(3);
+	allocate_threads(4);
 
 	/* Test all pending messages are reaped for the thread marked as exited. */
 	set_thread(0);
@@ -811,6 +811,14 @@ thread_exit(void)
 	spdk_io_device_unregister(&g_device1, NULL);
 	poll_threads();
 
+	/* Test call spdk_thread_exit() is only once for a single thread. */
+	set_thread(3);
+
+	thread = spdk_get_thread();
+
+	CU_ASSERT(spdk_thread_exit(thread) == 0);
+	CU_ASSERT(spdk_thread_exit(thread) == -EINVAL);
+
 	free_threads();
 }