diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -3547,24 +3547,28 @@
 	umtxq_insert(uq);
 	umtxq_unlock(&uq->uq_key);
 	rv = casueword32(&sem->_has_waiters, 0, &count1, 1);
-	if (rv == 0)
+	if (rv != -1)
 		rv1 = fueword32(&sem->_count, &count);
-	if (rv == -1 || (rv == 0 && (rv1 == -1 || count != 0)) ||
-	    (rv == 1 && count1 == 0)) {
+	if (rv == -1 || rv1 == -1 || count != 0 || (rv == 1 && count1 == 0)) {
+		if (rv == 0)
+			suword32(&sem->_has_waiters, 0);
 		umtxq_lock(&uq->uq_key);
 		umtxq_unbusy(&uq->uq_key);
 		umtxq_remove(uq);
 		umtxq_unlock(&uq->uq_key);
-		if (rv == 1) {
-			rv = thread_check_susp(td, true);
-			if (rv == 0)
-				goto again;
-			error = rv;
+		if (rv == -1 || rv1 == -1) {
+			error = EFAULT;
+			goto out;
+		}
+		if (count != 0) {
+			error = 0;
 			goto out;
 		}
+		MPASS(rv == 1 && count1 == 0);
+		rv = thread_check_susp(td, true);
 		if (rv == 0)
-			rv = rv1;
-		error = rv == -1 ? EFAULT : 0;
+			goto again;
+		error = rv;
 		goto out;
 	}
 	umtxq_lock(&uq->uq_key);