diff --git a/sys/kern/subr_autoconf.c b/sys/kern/subr_autoconf.c
index 121a18242abe..6415a1e7f4f6 100644
--- a/sys/kern/subr_autoconf.c
+++ b/sys/kern/subr_autoconf.c
@@ -1960,7 +1960,12 @@ config_detach_exit(device_t dev)
 {
 
 	mutex_enter(&config_misc_lock);
-	KASSERT(dev->dv_detaching == curlwp);
+	KASSERTMSG(dev->dv_detaching == curlwp,
+	    "lwp %ld [%s] @ %p detaching",
+	    (long)dev->dv_detaching->l_lid,
+	    (dev->dv_detaching->l_name ? dev->dv_detaching->l_name
+		: dev->dv_detaching->l_proc->p_comm),
+	    dev->dv_detaching);
 	dev->dv_detaching = NULL;
 	cv_broadcast(&config_misc_cv);
 	mutex_exit(&config_misc_lock);
@@ -2173,7 +2178,12 @@ config_detach_commit(device_t dev)
 {
 
 	mutex_enter(&config_misc_lock);
-	KASSERT(dev->dv_detaching == curlwp);
+	KASSERTMSG(dev->dv_detaching == curlwp,
+	    "lwp %ld [%s] @ %p detaching",
+	    (long)dev->dv_detaching->l_lid,
+	    (dev->dv_detaching->l_name ? dev->dv_detaching->l_name
+		: dev->dv_detaching->l_proc->p_comm),
+	    dev->dv_detaching);
 	dev->dv_detached = true;
 	cv_broadcast(&config_misc_cv);
 	mutex_exit(&config_misc_lock);