diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -4203,6 +4203,13 @@
 /* ARGSUSED */
 int
 nosys(struct thread *td, struct nosys_args *args)
+{
+
+	return (kern_nosys(td));
+}
+
+int
+kern_nosys(struct thread *td)
 {
 	struct proc *p;
 
diff --git a/sys/kern/kern_syscalls.c b/sys/kern/kern_syscalls.c
--- a/sys/kern/kern_syscalls.c
+++ b/sys/kern/kern_syscalls.c
@@ -51,14 +51,14 @@
 lkmnosys(struct thread *td, struct nosys_args *args)
 {
 
-	return (nosys(td, args));
+	return (kern_nosys(td));
 }
 
 int
 lkmressys(struct thread *td, struct nosys_args *args)
 {
 
-	return (nosys(td, args));
+	return (kern_nosys(td));
 }
 
 static void
diff --git a/sys/kern/subr_syscall.c b/sys/kern/subr_syscall.c
--- a/sys/kern/subr_syscall.c
+++ b/sys/kern/subr_syscall.c
@@ -58,7 +58,7 @@
 	struct syscall_args *sa;
 	struct sysent *se;
 	int error, traced;
-	bool sy_thr_static;
+	bool sy_thr_fast;
 
 	VM_CNT_INC(v_syscall);
 	p = td->td_proc;
@@ -138,15 +138,17 @@
 	KASSERT((td->td_pflags & TDP_NERRNO) == 0,
 	    ("%s: TDP_NERRNO set", __func__));
 
-	sy_thr_static = (se->sy_thrcnt & SY_THR_STATIC) != 0;
+	sy_thr_fast = (se->sy_thrcnt & (SY_THR_STATIC|SY_THR_ABSENT)) != 0;
 
 	if (__predict_false(SYSTRACE_ENABLED() ||
 	    AUDIT_SYSCALL_ENTER(sa->code, td) ||
-	    !sy_thr_static)) {
-		if (!sy_thr_static) {
+	    !sy_thr_fast)) {
+		if (!sy_thr_fast) {
 			error = syscall_thread_enter(td, se);
 			if (error != 0) {
 				td->td_errno = error;
+				if (error == ENOSYS)
+					(void)kern_nosys(td);
 				goto retval;
 			}
 		}
@@ -181,7 +183,7 @@
 			    error ? -1 : td->td_retval[0]);
 #endif
 
-		if (!sy_thr_static)
+		if (!sy_thr_fast)
 			syscall_thread_exit(td, se);
 	} else {
 		error = (se->sy_call)(td, sa->args);
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -197,6 +197,7 @@
 };
 
 int	nosys(struct thread *, struct nosys_args *);
+int	kern_nosys(struct thread *);
 
 #define	NO_SYSCALL (-1)
 
@@ -222,7 +223,7 @@
 	.sy_return = 0,						\
 	.sy_flags = 0,						\
 	.sy_thrcnt = 0						\
-}							
+}
 
 #define	MAKE_SYSENT(syscallname)				\
 static struct sysent syscallname##_sysent = SYSENT_INIT_VALS(syscallname);
diff --git a/tests/sys/kern/Makefile b/tests/sys/kern/Makefile
--- a/tests/sys/kern/Makefile
+++ b/tests/sys/kern/Makefile
@@ -27,6 +27,7 @@
 ATF_TESTS_C+=	reaper
 ATF_TESTS_C+=	sched_affinity
 ATF_TESTS_C+=	sigaltstack
+ATF_TESTS_C+=	sigsys
 ATF_TESTS_C+=	sigwait
 ATF_TESTS_C+=	socket_accf
 ATF_TESTS_C+=	socket_msg_trunc
diff --git a/tests/sys/kern/sigsys.c b/tests/sys/kern/sigsys.c
new file mode 100644
--- /dev/null
+++ b/tests/sys/kern/sigsys.c
@@ -0,0 +1,67 @@
+/*-
+ * Copyright (c) 2023 Dmitry Chagin <dchagin@FreeBSD.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sys/syscall.h>
+
+#include <atf-c.h>
+#include <errno.h>
+#include <signal.h>
+
+static volatile sig_atomic_t signals = 0;
+static volatile sig_atomic_t signo = 0;
+
+static void
+handler(int sig)
+{
+
+	signo = sig;
+	signals++;
+}
+
+ATF_TC(test_sigsys);
+ATF_TC_HEAD(test_sigsys, tc)
+{
+
+	atf_tc_set_md_var(tc, "descr", "Check SIGSYS");
+}
+
+ATF_TC_BODY(test_sigsys, tc)
+{
+	int error;
+
+	ATF_REQUIRE(signal(SIGSYS, handler) != SIG_ERR);
+
+	/* 11 - obsolete execv */
+	error = syscall(11, 0, 1);
+	ATF_REQUIRE(error == -1);
+	ATF_REQUIRE(errno == ENOSYS);
+	ATF_REQUIRE(signals == 1);
+	ATF_REQUIRE(signo == SIGSYS);
+
+	/* loadable syscall */
+	signals = signo = 0;
+	error = syscall(SYS_nfssvc, 0, 1);
+	ATF_REQUIRE(error == -1);
+	ATF_REQUIRE(errno == ENOSYS || errno == EINVAL);
+	ATF_REQUIRE(signals == 0 || signals == 1);
+	ATF_REQUIRE(signo == SIGSYS || signo == 0);
+
+	/* non-existent syscall */
+	signals = signo = 0;
+	error = syscall(SYS_MAXSYSCALL + 1, 0, 1);
+	ATF_REQUIRE(error == -1);
+	ATF_REQUIRE(errno == ENOSYS);
+	ATF_REQUIRE(signals == 1);
+	ATF_REQUIRE(signo == SIGSYS);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, test_sigsys);
+
+	return (atf_no_error());
+}