Index: sys/kern/kern_event.c
===================================================================
--- sys/kern/kern_event.c
+++ sys/kern/kern_event.c
@@ -1122,6 +1122,9 @@
 	haskqglobal = 0;
 	filedesc_unlock = 0;
 
+	if ((kev->flags & (EV_ENABLE | EV_DISABLE)) == (EV_ENABLE | EV_DISABLE))
+		return (EINVAL);
+
 	filt = kev->filter;
 	fops = kqueue_fo_find(filt);
 	if (fops == NULL)
@@ -1320,27 +1323,24 @@
 	 * kn_knlist.
 	 */
 done_ev_add:
-	if ((kev->flags & EV_DISABLE) &&
-	    ((kn->kn_status & KN_DISABLED) == 0)) {
+	if ((kev->flags & EV_ENABLE) != 0)
+		kn->kn_status &= ~KN_DISABLED;
+	else if ((kev->flags & EV_DISABLE) != 0)
 		kn->kn_status |= KN_DISABLED;
-	}
 
 	if ((kn->kn_status & KN_DISABLED) == 0)
 		event = kn->kn_fop->f_event(kn, 0);
 	else
 		event = 0;
+
 	KQ_LOCK(kq);
 	if (event)
 		KNOTE_ACTIVATE(kn, 1);
+	else if ((kn->kn_status & (KN_ACTIVE | KN_DISABLED | KN_QUEUED)) ==
+	    KN_ACTIVE)
+		knote_enqueue(kn);
 	kn->kn_status &= ~(KN_INFLUX | KN_SCAN);
 	KN_LIST_UNLOCK(kn);
-
-	if ((kev->flags & EV_ENABLE) && (kn->kn_status & KN_DISABLED)) {
-		kn->kn_status &= ~KN_DISABLED;
-		if ((kn->kn_status & KN_ACTIVE) &&
-		    ((kn->kn_status & KN_QUEUED) == 0))
-			knote_enqueue(kn);
-	}
 	KQ_UNLOCK_FLUX(kq);
 
 done:
Index: tests/sys/kqueue/read.c
===================================================================
--- tests/sys/kqueue/read.c
+++ tests/sys/kqueue/read.c
@@ -124,15 +124,17 @@
 
     test_begin(test_id);
 
-    /* Add an event, then disable it. */
-    EV_SET(&kev, sockfd[0], EVFILT_READ, EV_ADD, 0, 0, &sockfd[0]);
-    if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
-        err(1, "%s", test_id);
-    EV_SET(&kev, sockfd[0], EVFILT_READ, EV_DISABLE, 0, 0, &sockfd[0]);
+    /*
+     * Write to the socket before adding the event. This way we can verify that
+     * enabling a triggered kevent causes the event to be returned immediately.
+     */
+    kevent_socket_fill();
+
+    /* Add a disabled event. */
+    EV_SET(&kev, sockfd[0], EVFILT_READ, EV_ADD | EV_DISABLE, 0, 0, &sockfd[0]);
     if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
         err(1, "%s", test_id);
 
-    kevent_socket_fill();
     test_no_kevents();
 
     /* Re-enable the knote, then see if an event is generated */