diff --git a/tests/Makefile.am b/tests/Makefile.am
index ff3175d..0b79ed6 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -45,6 +45,7 @@
 	error_msg.c \
 	tail_alloc.c \
 	tests.h \
+	tprintf.c \
 	# end of libtests_a_SOURCES
 libtests_a_CPPFLAGS = $(AM_CPPFLAGS) -D_FILE_OFFSET_BITS=64
 check_LIBRARIES = libtests.a
diff --git a/tests/mmsg.c b/tests/mmsg.c
index fa1ee8b..ba6cfe4 100644
--- a/tests/mmsg.c
+++ b/tests/mmsg.c
@@ -47,8 +47,6 @@
 
 # define LENGTH_OF(arg) ((unsigned int) sizeof(arg) - 1)
 
-static FILE *logfp;
-
 static int
 send_mmsg(int fd, struct mmsghdr *vec, unsigned int vlen, unsigned int flags)
 {
@@ -58,8 +56,7 @@
 		     (unsigned long) flags);
 	if (rc >= 0 || ENOSYS != errno)
 		return rc;
-	fprintf(logfp,
-		"sendmmsg(%d, %p, %u, MSG_DONTROUTE|MSG_NOSIGNAL)"
+	tprintf("sendmmsg(%d, %p, %u, MSG_DONTROUTE|MSG_NOSIGNAL)"
 		" = -1 ENOSYS (%m)\n", fd, vec, vlen);
 #endif
 #ifdef HAVE_SENDMMSG
@@ -78,8 +75,7 @@
 		     (unsigned long) flags, timeout);
 	if (rc >= 0 || ENOSYS != errno)
 		return rc;
-	fprintf(logfp,
-		"recvmmsg(%d, %p, %u, MSG_DONTWAIT, NULL)"
+	tprintf("recvmmsg(%d, %p, %u, MSG_DONTWAIT, NULL)"
 		" = -1 ENOSYS (%m)\n", fd, vec, vlen);
 #endif
 #ifdef HAVE_RECVMMSG
@@ -91,15 +87,10 @@
 int
 main(void)
 {
+	tprintf("%s", "");
+
 	const int R = 0, W = 1;
 	int sv[2];
-
-	int logfd = dup(1);
-	assert(logfd > 2);
-	assert((logfp = fdopen(logfd, "w")));
-
-	(void) close(0);
-	(void) close(1);
 	if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sv))
 		perror_msg_and_skip("socketpair");
 	assert(R == sv[0]);
@@ -151,8 +142,7 @@
 		perror_msg_and_skip("sendmmsg");
 	assert(r == (int) n_mmh);
 	assert(close(W) == 0);
-	fprintf(logfp,
-		"sendmmsg(%d, {{{msg_name(0)=NULL, msg_iov(%u)=[{\"%s\", %u}"
+	tprintf("sendmmsg(%d, {{{msg_name(0)=NULL, msg_iov(%u)=[{\"%s\", %u}"
 		", {\"%s\", %u}], msg_controllen=0, msg_flags=0}, %u}"
 		", {{msg_name(0)=NULL, msg_iov(%u)=[{\"%s\", %u}]"
 		", msg_controllen=0, msg_flags=0}, %u}}, %u"
@@ -166,7 +156,7 @@
 		" * %u bytes in buffer 0\n"
 		" | 00000  %-48s  %-16s |\n",
 		W, 2, one, LENGTH_OF(one), two, LENGTH_OF(two),
-		LENGTH_OF(one) +  LENGTH_OF(two),
+		LENGTH_OF(one) + LENGTH_OF(two),
 		1, three, LENGTH_OF(three), LENGTH_OF(three),
 		n_mmh, r,
 		2, LENGTH_OF(one), ascii_one, one,
@@ -175,8 +165,7 @@
 
 	assert(recv_mmsg(R, copy_mmh, n_mmh, MSG_DONTWAIT, NULL) == (int) n_mmh);
 	assert(close(R) == 0);
-	fprintf(logfp,
-		"recvmmsg(%d, {{{msg_name(0)=NULL, msg_iov(%u)=[{\"%s\", %u}"
+	tprintf("recvmmsg(%d, {{{msg_name(0)=NULL, msg_iov(%u)=[{\"%s\", %u}"
 		", {\"%s\", %u}], msg_controllen=0, msg_flags=0}, %u}"
 		", {{msg_name(0)=NULL, msg_iov(%u)=[{\"%s\", %u}]"
 		", msg_controllen=0, msg_flags=0}, %u}}, %u"
@@ -190,14 +179,14 @@
 		" * %u bytes in buffer 0\n"
 		" | 00000  %-48s  %-16s |\n",
 		R, 2, one, LENGTH_OF(one), two, LENGTH_OF(two),
-		LENGTH_OF(one) +  LENGTH_OF(two),
+		LENGTH_OF(one) + LENGTH_OF(two),
 		1, three, LENGTH_OF(three), LENGTH_OF(three),
 		n_mmh, r,
 		2, LENGTH_OF(one), ascii_one, one,
 		LENGTH_OF(two), ascii_two, two,
 		1, LENGTH_OF(three), ascii_three, three);
 
-	fprintf(logfp, "+++ exited with 0 +++\n");
+	tprintf("+++ exited with 0 +++\n");
 	return 0;
 }
 
diff --git a/tests/tests.h b/tests/tests.h
index 36ddea3..e69e4d1 100644
--- a/tests/tests.h
+++ b/tests/tests.h
@@ -59,6 +59,10 @@
 void *tail_memdup(const void *, const size_t)
 	ATTRIBUTE_MALLOC ATTRIBUTE_ALLOC_SIZE((2));
 
+/* Close stdin, move stdout to a non-standard descriptor, and print. */
+void tprintf(const char *, ...)
+	ATTRIBUTE_FORMAT((printf, 1, 2));
+
 # define SKIP_MAIN_UNDEFINED(arg) \
 	int main(void) { error_msg_and_skip("undefined: %s", arg); }
 
diff --git a/tests/tprintf.c b/tests/tprintf.c
new file mode 100644
index 0000000..a759d8a
--- /dev/null
+++ b/tests/tprintf.c
@@ -0,0 +1,90 @@
+/*
+ * Close stdin, move stdout to a non-standard descriptor, and print.
+ *
+ * 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 <assert.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static ssize_t
+write_retry(int fd, const void *buf, size_t count)
+{
+	ssize_t rc;
+
+	do {
+		errno = 0;
+		rc = write(fd, buf, count);
+	} while (rc == -1 && EINTR == errno);
+
+	if (rc <= 0)
+		perror_msg_and_fail("write");
+
+	return rc;
+}
+
+static void
+write_loop(int fd, const char *buf, size_t count)
+{
+	ssize_t offset = 0;
+
+	while (count > 0) {
+		ssize_t block = write_retry(fd, &buf[offset], count);
+
+		offset += block;
+		count -= (size_t) block;
+	}
+}
+
+void
+tprintf(const char *fmt, ...)
+{
+	static int initialized;
+	if (!initialized) {
+		assert(dup2(1, 3) == 3);
+		assert(close(1) == 0);
+		(void) close(0);
+		initialized = 1;
+	}
+
+	va_list p;
+	va_start(p, fmt);
+
+	static char buf[65536];
+	int len = vsnprintf(buf, sizeof(buf), fmt, p);
+	if (len < 0)
+		perror_msg_and_fail("vsnprintf");
+	assert((unsigned) len < sizeof(buf));
+
+	write_loop(3, buf, len);
+
+	va_end(p);
+}