diff --git a/Makefile.am b/Makefile.am
index a00a682..f8b13c8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -7,4 +7,5 @@ MAINTAINERCLEANFILES = \
 SUBDIRS = lib src
 if BUILD_TESTTOOLS
 SUBDIRS += nvtsrv
+SUBDIRS += nvttest
 endif
diff --git a/configure.ac b/configure.ac
index c77efe5..fd7278d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,6 +43,7 @@ Makefile
 lib/Makefile
 src/Makefile
 nvtsrv/Makefile
+nvttest/Makefile
 ])
 AC_OUTPUT
 
diff --git a/nvttest/Makefile.am b/nvttest/Makefile.am
new file mode 100644
index 0000000..ab13e79
--- /dev/null
+++ b/nvttest/Makefile.am
@@ -0,0 +1,7 @@
+
+bin_PROGRAMS = nvttest
+
+nvttest_SOURCES = \
+	nvttest.c
+
+nvttest_CPPFLAGS = -I$(top_builddir) -I$(top_srcdir) $(CFLAGS_WARN)
diff --git a/nvttest/nvttest.c b/nvttest/nvttest.c
new file mode 100644
index 0000000..89c98d7
--- /dev/null
+++ b/nvttest/nvttest.c
@@ -0,0 +1,144 @@
+/*
+ * ttynvt stress tool
+ */
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <fcntl.h>
+
+#include <sys/ioctl.h>
+#include <asm/termbits.h>
+
+
+static const char *dev = "/dev/ttyNVT0";
+
+typedef struct {
+    int             nthread;
+    int             ithread;
+    int             nloop;
+    bool            opt_rand_delay;
+} topts_t;
+
+static void    *_worker(void *arg)
+{
+    topts_t        *topts = arg;
+    int             iloop;
+    int             fd, err, nw;
+    struct termios  ios;
+
+    for (iloop = 0; iloop < topts->nloop; iloop++)
+    {
+        printf("Thread %d/%d run %d/%d\n",
+               topts->ithread, topts->nthread, iloop + 1, topts->nloop);
+        {
+            fd = open(dev, O_RDWR);
+            if (fd < 0)
+            {
+                printf("Open '%s' failed: %m\n", dev);
+                break;
+            }
+
+            memset(&ios, 0, sizeof(ios));
+            err = ioctl(fd, TCGETS, &ios);
+            if (err != 0)
+            {
+                printf("ioctl(TCGETS) failed: %m\n");
+                break;
+            }
+            err = ioctl(fd, TCSETS, &ios);
+            if (err != 0)
+            {
+                printf("ioctl(TCSETS) failed: %m\n");
+                break;
+            }
+            close(fd);
+        }
+
+        {
+            fd = open(dev, O_RDWR);
+            if (fd < 0)
+            {
+                printf("Open '%s' failed: %m\n", dev);
+                break;
+            }
+
+            nw = dprintf(fd, "Hallo\n");
+            if (nw <= 0)
+            {
+                printf("write failed: %m\n");
+                break;
+            }
+            close(fd);
+        }
+
+        if (topts->opt_rand_delay)
+            usleep(rand() & 0xfff);
+    }
+
+    return NULL;
+}
+
+int main(int argc, char **argv)
+{
+    int             err;
+    int             opt;
+    int             ithr, nthr;
+    topts_t         topts = { }, *popts;
+    pthread_t      *ptids;
+
+    nthr = 1;
+    topts.nloop = 1;
+
+    while ((opt = getopt(argc, argv, "n:rt:")) != -1)
+    {
+        switch (opt)
+        {
+        case 'n':
+            topts.nloop = atoi(optarg);
+            break;
+        case 'r':
+            topts.opt_rand_delay = true;
+            break;
+        case 't':
+            nthr = atoi(optarg);
+            break;
+        default:               /* '?' */
+            fprintf(stderr, "Usage: %s [-n nloop]\n", argv[0]);
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    topts.nthread = nthr;
+
+    ptids = malloc(nthr * sizeof(pthread_t));
+
+    for (ithr = 0; ithr < nthr; ithr++)
+    {
+        printf("Create worker thread %d/%d\n", ithr + 1, nthr);
+
+        popts = malloc(sizeof(topts_t));
+        *popts = topts;
+        popts->ithread = ithr + 1;
+
+        err = pthread_create(&ptids[ithr], NULL, _worker, popts);
+        if (err)
+        {
+            printf("Failed to create thread %d/%d\n", ithr, nthr);
+            break;
+        }
+    }
+
+    for (ithr = 0; ithr < nthr; ithr++)
+    {
+        if (ptids[ithr] == 0)
+            break;
+        pthread_join(ptids[ithr], NULL);
+        printf("Joined worker thread %d/%d\n", ithr + 1, nthr);
+    }
+
+    return 0;
+}