diff --git a/signal.c b/signal.c
index c13308d..d0f0b08 100644
--- a/signal.c
+++ b/signal.c
@@ -660,32 +660,30 @@
 	if (entering(tcp)) {
 		print_sigset_addr_len(tcp, tcp->u_arg[0], tcp->u_arg[3]);
 		tprints(", ");
-		/* This is the only "return" parameter, */
-		if (tcp->u_arg[1] != 0)
-			return 0;
-		/* ... if it's NULL, can decode all on entry */
-		tprints("NULL, ");
-	}
-	else if (tcp->u_arg[1] != 0) {
-		/* syscall exit, and u_arg[1] wasn't NULL */
-		printsiginfo_at(tcp, tcp->u_arg[1]);
-		tprints(", ");
-	}
-	else {
-		/* syscall exit, and u_arg[1] was NULL */
-		return 0;
-	}
+		if (!tcp->u_arg[1]) {
+			/*
+			 * This is the only "return" parameter,
+			 * if it's NULL, decode all parameters on entry.
+			 */
+			tprints("NULL, ");
+			print_timespec(tcp, tcp->u_arg[2]);
+			tprintf(", %lu", tcp->u_arg[3]);
+			tcp->auxstr = NULL;
+		} else {
+			tcp->auxstr = sprint_timespec(tcp, tcp->u_arg[2]);
+		}
+	} else {
+		if (tcp->auxstr) {
+			printsiginfo_at(tcp, tcp->u_arg[1]);
+			tprintf(", %s, %lu", tcp->auxstr, tcp->u_arg[3]);
+			tcp->auxstr = NULL;
+		}
 
-	/*
-	 * Since the timeout parameter is read by the kernel
-	 * on entering syscall, it has to be decoded the same way
-	 * whether the syscall has failed or not.
-	 */
-	temporarily_clear_syserror(tcp);
-	print_timespec(tcp, tcp->u_arg[2]);
-	restore_cleared_syserror(tcp);
-
-	tprintf(", %lu", tcp->u_arg[3]);
+		if (!syserror(tcp) && tcp->u_rval) {
+			tcp->auxstr = signame(tcp->u_rval);
+			return RVAL_STR;
+		}
+	}
 	return 0;
 };
 
diff --git a/tests/.gitignore b/tests/.gitignore
index c701874..a37c052 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -84,6 +84,7 @@
 rt_sigpending
 rt_sigprocmask
 rt_sigqueueinfo
+rt_sigtimedwait
 sched_xetaffinity
 sched_xetattr
 scm_rights
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7030a29..de9bfb1 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -132,6 +132,7 @@
 	rt_sigpending \
 	rt_sigprocmask \
 	rt_sigqueueinfo \
+	rt_sigtimedwait \
 	sched_xetaffinity \
 	sched_xetattr \
 	scm_rights \
@@ -284,6 +285,7 @@
 	rt_sigpending.test \
 	rt_sigprocmask.test \
 	rt_sigqueueinfo.test \
+	rt_sigtimedwait.test \
 	sched_xetaffinity.test \
 	sched_xetattr.test \
 	scm_rights-fd.test \
diff --git a/tests/rt_sigtimedwait.c b/tests/rt_sigtimedwait.c
new file mode 100644
index 0000000..6136b7c
--- /dev/null
+++ b/tests/rt_sigtimedwait.c
@@ -0,0 +1,182 @@
+/*
+ * This file is part of rt_sigtimedwait strace test.
+ *
+ * Copyright (c) 2016 Dmitry V. Levin <ldv@altlinux.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "tests.h"
+#include <sys/syscall.h>
+
+#ifdef __NR_rt_sigtimedwait
+
+# include <assert.h>
+# include <errno.h>
+# include <signal.h>
+# include <stdio.h>
+# include <stdint.h>
+# include <string.h>
+# include <unistd.h>
+
+static long
+k_sigtimedwait(const sigset_t *const set, siginfo_t *const info,
+	       const struct timespec *const timeout, const unsigned long size)
+{
+	return syscall(__NR_rt_sigtimedwait, set, info, timeout, size);
+}
+
+static void
+iterate(const char *const text, const void *set,
+	const struct timespec *const timeout, unsigned int size)
+{
+	for (;;) {
+		assert(k_sigtimedwait(set, NULL, timeout, size) == -1);
+		if (EINTR == errno) {
+			tprintf("rt_sigtimedwait(%s, NULL, {%jd, %jd}, %u)"
+				" = -1 EAGAIN (%m)\n", text,
+				(intmax_t) timeout->tv_sec,
+				(intmax_t) timeout->tv_nsec,
+				size);
+		} else {
+			if (size < sizeof(long))
+				tprintf("rt_sigtimedwait(%p, NULL, {%jd, %jd}"
+					", %u) = -1 EINVAL (%m)\n",
+					set, (intmax_t) timeout->tv_sec,
+					(intmax_t) timeout->tv_nsec, size);
+			else
+				tprintf("rt_sigtimedwait(%s, NULL, {%jd, %jd}"
+					", %u) = -1 EINVAL (%m)\n",
+					text, (intmax_t) timeout->tv_sec,
+					(intmax_t) timeout->tv_nsec, size);
+		}
+		if (!size)
+			break;
+		size >>= 1;
+		set += size;
+	}
+}
+
+int
+main(void)
+{
+	tprintf("%s", "");
+
+	siginfo_t *const info = tail_alloc(sizeof(*info));
+	struct timespec *const timeout = tail_alloc(sizeof(*timeout));
+	timeout->tv_sec = 0;
+	timeout->tv_nsec = 42;
+
+	const unsigned int big_size = 1024 / 8;
+	void *k_set = tail_alloc(big_size);
+	memset(k_set, 0, big_size);
+
+	unsigned int set_size = big_size;
+	for (; set_size; set_size >>= 1, k_set += set_size) {
+		assert(k_sigtimedwait(k_set, NULL, timeout, set_size) == -1);
+		if (EAGAIN == errno)
+			break;
+		tprintf("rt_sigtimedwait(%p, NULL, {%jd, %jd}, %u)"
+			" = -1 EINVAL (%m)\n",
+			k_set, (intmax_t) timeout->tv_sec,
+			(intmax_t) timeout->tv_nsec, set_size);
+	}
+	if (!set_size)
+		perror_msg_and_fail("rt_sigtimedwait");
+	tprintf("rt_sigtimedwait([], NULL, {%jd, %jd}, %u) = -1 EAGAIN (%m)\n",
+		(intmax_t) timeout->tv_sec, (intmax_t) timeout->tv_nsec,
+		set_size);
+
+	sigset_t *const libc_set = tail_alloc(sizeof(sigset_t));
+	sigemptyset(libc_set);
+	sigaddset(libc_set, SIGHUP);
+	memcpy(k_set, libc_set, set_size);
+
+	assert(k_sigtimedwait(k_set, info, timeout, set_size) == -1);
+	assert(EAGAIN == errno);
+	tprintf("rt_sigtimedwait([HUP], %p, {%jd, %jd}, %u) = -1 EAGAIN (%m)\n",
+		info, (intmax_t) timeout->tv_sec,
+		(intmax_t) timeout->tv_nsec, set_size);
+
+	sigaddset(libc_set, SIGINT);
+	memcpy(k_set, libc_set, set_size);
+
+	assert(k_sigtimedwait(k_set, info, timeout, set_size) == -1);
+	assert(EAGAIN == errno);
+	tprintf("rt_sigtimedwait([HUP INT], %p, {%jd, %jd}, %u)"
+		" = -1 EAGAIN (%m)\n",
+		info, (intmax_t) timeout->tv_sec,
+		(intmax_t) timeout->tv_nsec, set_size);
+
+	sigaddset(libc_set, SIGQUIT);
+	sigaddset(libc_set, SIGALRM);
+	sigaddset(libc_set, SIGTERM);
+	memcpy(k_set, libc_set, set_size);
+
+	assert(k_sigtimedwait(k_set, info, timeout, set_size) == -1);
+	assert(EAGAIN == errno);
+	tprintf("rt_sigtimedwait(%s, %p, {%jd, %jd}, %u) = -1 EAGAIN (%m)\n",
+		"[HUP INT QUIT ALRM TERM]",
+		info, (intmax_t) timeout->tv_sec,
+		(intmax_t) timeout->tv_nsec, set_size);
+
+	memset(k_set - set_size, -1, set_size);
+	assert(k_sigtimedwait(k_set - set_size, info, timeout, set_size) == -1);
+	assert(EAGAIN == errno);
+	tprintf("rt_sigtimedwait(~[], %p, {%jd, %jd}, %u) = -1 EAGAIN (%m)\n",
+		info, (intmax_t) timeout->tv_sec,
+		(intmax_t) timeout->tv_nsec, set_size);
+
+	if (sigprocmask(SIG_SETMASK, libc_set, NULL))
+		perror_msg_and_fail("sigprocmask");
+
+	assert(k_sigtimedwait(k_set - set_size, info, NULL, set_size << 1) == -1);
+	tprintf("rt_sigtimedwait(%p, %p, NULL, %u) = -1 EINVAL (%m)\n",
+		k_set - set_size, info, set_size << 1);
+
+	iterate("~[]", k_set - set_size, timeout, set_size >> 1);
+
+	timeout->tv_sec = 1;
+	raise(SIGALRM);
+	assert(k_sigtimedwait(k_set, info, timeout, set_size) == SIGALRM);
+	tprintf("rt_sigtimedwait(%s, {si_signo=%s, si_code=SI_TKILL"
+		", si_pid=%d, si_uid=%d}, {%jd, %jd}, %u) = %d (%s)\n",
+		"[HUP INT QUIT ALRM TERM]", "SIGALRM", getpid(), getuid(),
+		(intmax_t) timeout->tv_sec, (intmax_t) timeout->tv_nsec,
+		set_size, SIGALRM, "SIGALRM");
+
+	raise(SIGALRM);
+	assert(k_sigtimedwait(k_set, NULL, NULL, set_size) == SIGALRM);
+	tprintf("rt_sigtimedwait(%s, NULL, NULL, %u) = %d (%s)\n",
+		"[HUP INT QUIT ALRM TERM]", set_size, SIGALRM, "SIGALRM");
+
+	tprintf("+++ exited with 0 +++\n");
+	return 0;
+}
+
+#else
+
+SKIP_MAIN_UNDEFINED("__NR_rt_sigtimedwait")
+
+#endif
diff --git a/tests/rt_sigtimedwait.test b/tests/rt_sigtimedwait.test
new file mode 100755
index 0000000..b8ff2e1
--- /dev/null
+++ b/tests/rt_sigtimedwait.test
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# Check rt_sigtimedwait syscall decoding.
+
+. "${srcdir=.}/init.sh"
+
+run_prog > /dev/null
+OUT="$LOG.out"
+run_strace -a38 -ert_sigtimedwait $args > "$OUT"
+match_diff "$LOG" "$OUT"
+rm -f "$OUT"