diff --git a/.gitignore b/.gitignore
index 34b4b2c..e2322b4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -49,3 +49,4 @@ apps/readdir
 apps/loader
 apps/asciivju
 apps/justawindow
+test/runtests
diff --git a/makefile b/makefile
index 804d947..5c80ec8 100644
--- a/makefile
+++ b/makefile
@@ -50,10 +50,9 @@ endif
 
 ifeq ($(HOST),linux)
 all: umka_shell umka_fuse umka_os umka_gen_devices_dat umka.sym umka.prp \
-     umka.lst tags default.skn skin.skn
+     umka.lst tags default.skn skin.skn test/runtests
 else ifeq ($(HOST),windows)
-all: umka_shell umka.sym umka.prp \
-     umka.lst default.skn skin.skn
+all: umka_shell umka.sym umka.prp umka.lst default.skn skin.skn test/runtests
 else
         $(error your OS is not supported)
 endif
@@ -102,9 +101,8 @@ $(HOST)/pci.o: $(HOST)/pci.c
 	$(CC) $(CFLAGS_32) -std=gnu11 -c $< -o $@
 
 deps/lodepng/lodepng.o: deps/lodepng/lodepng.c deps/lodepng/lodepng.h
-	$(CC) $(CFLAGS_32) -c $< -DLODEPNG_NO_COMPILE_ZLIB \
-                -DLODEPNG_NO_COMPILE_DECODER -DLODEPNG_NO_COMPILE_DISK \
-                -DLODEPNG_NO_COMPILE_ANCILLARY_CHUNKS -DLODEPNG_NO_COMPILE_CRC
+	$(CC) $(CFLAGS_32) -c $< -o $@ -DLODEPNG_NO_COMPILE_DECODER \
+                -DLODEPNG_NO_COMPILE_ZLIB -DLODEPNG_NO_COMPILE_ANCILLARY_CHUNKS
 
 deps/isocline/src/isocline.o: deps/isocline/src/isocline.c \
         deps/isocline/include/isocline.h
@@ -181,10 +179,18 @@ umka_os.o: umka_os.c umka.h
 umka_gen_devices_dat.o: umka_gen_devices_dat.c umka.h
 	$(CC) $(CFLAGS_32) -c $<
 
+test/runtests: test/runtests.o deps/optparse/optparse.o
+	$(CC) $(LDFLAGS_32) -o $@ $^
+
+test/runtests.o: test/runtests.c
+	$(CC) $(CFLAGS_32) -c $< -o $@ -Wno-deprecated-declarations
+
+
 .PHONY: all clean
 
 clean:
 	rm -f umka_shell umka_fuse umka_os umka_gen_devices_dat umka.fas \
-          umka.sym umka.lst umka.prp umka.cov coverage *.skn colors.dtp
+          umka.sym umka.lst umka.prp umka.cov coverage *.skn colors.dtp \
+          test/runtests
 	find . -name "*.o" -delete
 	find . -name "*.a" -delete
diff --git a/test/runtests.c b/test/runtests.c
new file mode 100644
index 0000000..2b31218
--- /dev/null
+++ b/test/runtests.c
@@ -0,0 +1,262 @@
+/*
+    SPDX-License-Identifier: GPL-2.0-or-later
+
+    UMKa - User-Mode KolibriOS developer tools
+    runtests - the test runner
+
+    Copyright (C) 2023  Ivan Baravy <dunkaist@gmail.com>
+*/
+
+#include <dirent.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <threads.h>
+#include <unistd.h>
+
+#include <pthread.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "optparse/optparse.h"
+
+#ifndef PATH_MAX
+#define PATH_MAX 0x1000
+#endif
+
+#define CMPFILE_BUF_LEN 0x100000
+#define TIMEOUT_FILENAME "timeout.txt"
+#define TIMEOUT_STR_MAX_LEN 16
+#define ACTION_RUN 0
+
+thread_local char bufa[CMPFILE_BUF_LEN];
+thread_local char bufb[CMPFILE_BUF_LEN];
+thread_local char outfname[PATH_MAX];
+thread_local char timeoutfname[PATH_MAX];
+
+int silent_success = 1;
+
+static int
+is_valid_test_name(const char *name) {
+    if (name[0] != 't') {
+        return 0;
+    }
+    for (size_t i = 1; i < 4 && name[i]; i++) {
+        if (name[1] < '0' || name[1] > '9') {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+static int
+cmpfile(const char *fnamea, const char *fnameb) {
+    FILE *filea = fopen(fnamea, "rb");
+    if (!filea) {
+        fprintf(stderr, "Can't open file '%s' for reading: %s\n", fnamea,
+                strerror(errno));
+        return -1;
+    }
+    FILE *fileb = fopen(fnameb, "rb");
+    if (!fileb) {
+        fprintf(stderr, "Can't open file '%s' for reading: %s\n", fnameb,
+                strerror(errno));
+        return -1;
+    }
+    while (1) {
+        size_t reada = fread(bufa, CMPFILE_BUF_LEN, 1, filea);
+        size_t readb = fread(bufa, CMPFILE_BUF_LEN, 1, fileb);
+        if (reada != readb || memcmp(bufa, bufb, reada)) {
+            fprintf(stderr, "[!] files %s and %s don't match\n", fnamea,
+                    fnameb);
+            return -1;
+        }
+    }
+    fclose(filea);
+    fclose(fileb);
+    return 0;
+}
+
+static int
+check_test_artefacts(const char *testname) {
+    DIR *tdir = opendir(".");
+    if (!tdir) {
+        fprintf(stderr, "Can't open directory '%s': %s\n", testname,
+                strerror(errno));
+        return -1;
+    }
+
+    struct dirent dent;
+    struct dirent *result;
+    const char *reffname;
+    while (readdir_r(tdir, &dent, &result)) {
+        reffname = dent.d_name;
+        const char *dotrefdot = strstr(reffname, ".ref.");
+        if (!dotrefdot) {
+            continue;
+        }
+        strcpy(outfname, reffname);
+        memcpy(outfname + (dotrefdot - reffname), ".out.", 5);
+        if (cmpfile(reffname, outfname)) {
+            return -1;
+        }
+    }
+    closedir(tdir);
+    return 0;
+}
+
+struct test_wait_arg {
+    int pid;
+    pthread_cond_t *cond;
+};
+
+static unsigned
+get_test_timeout(const char *testname) {
+    sprintf(timeoutfname, "%s/%s", testname, TIMEOUT_FILENAME);
+    FILE *f = fopen(timeoutfname, "rb");
+    if (!f) {
+        fprintf(stderr, "[!] Can't open %s\n: %s\n", TIMEOUT_FILENAME,
+                strerror(errno));
+        return 0;
+    }
+    char str[TIMEOUT_STR_MAX_LEN];
+    fread(str, 1, TIMEOUT_STR_MAX_LEN, f);
+    fclose(f);
+    unsigned n, sec = 0, min = 0;
+    char *end;
+    n = strtoul(str, &end, 0);
+    switch (*end) {
+    case 's':
+        sec = n;
+        break;
+    case 'm':
+        min = n;
+        sec = strtoul(end+1, &end, 0);
+        break;
+    default:
+        fprintf(stderr, "[!] bad timeout value: %s\n", str);
+        return 0;
+    }
+    return min*60 + sec;
+}
+
+#ifndef _WIN32
+static void *
+thread_wait(void *arg) {
+    struct test_wait_arg *wa = arg;
+    int status;
+    waitpid(wa->pid, &status, 0);
+    pthread_cond_signal(wa->cond);
+    return (void *)(intptr_t)status;
+}
+
+static void *
+run_test(const void *arg) {
+    const char *test_name = arg;
+    void *result = NULL;
+    pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+    pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+    pthread_mutex_lock(&mutex);
+    int child;
+    if (!(child = fork())) {
+        chdir(test_name);
+        execl("../../umka_shell", "../../umka_shell", "-ri", "run.us", "-o",
+              "out.log", NULL);
+        fprintf(stderr, "Can't run test command: %s\n", strerror(errno));
+        return (void *)-1;
+    }
+    pthread_t t;
+    struct test_wait_arg wa = {.pid = child, .cond = &cond};
+    pthread_create(&t, NULL, thread_wait, &wa);
+    unsigned tout = get_test_timeout(test_name);
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    ts.tv_sec += tout;
+    int status;
+    if ((status = pthread_cond_timedwait(&cond, &mutex, &ts))) {
+        fprintf(stderr, "[!] %s: timeout (%um%us)\n", test_name,
+                tout/60, tout % 60);
+        kill(child, SIGKILL);
+        result = (void *)(intptr_t)status;
+    }
+    pthread_join(t, &result);
+    pthread_mutex_unlock(&mutex);
+    
+    return result;
+}
+#else
+static void *
+run_test(void *arg) {
+    const char *test_name = arg;
+
+    return (void *)-1;
+}
+#endif
+
+pthread_mutex_t readdir_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void *
+thread_run_test(void *arg) {
+    DIR *cwd = arg;
+    struct dirent *dent;
+    while (1) {
+        pthread_mutex_lock(&readdir_mutex);
+        dent = readdir(cwd);
+        pthread_mutex_unlock(&readdir_mutex);
+        if (!dent) {
+            break;
+        }
+        const char *testname = dent->d_name;
+        if (!is_valid_test_name(testname)) {
+            continue;
+        }
+        fprintf(stderr, "running test %s\n", testname);
+        if (run_test(testname) || check_test_artefacts(testname)) {
+            fprintf(stderr, "[!] test %s failed\n", testname);
+        } else if (!silent_success) {
+                fprintf(stderr, "test %s ok\n", testname);
+        }
+    }
+    return NULL;
+}
+
+int
+main(int argc, char *argv[]) {
+    (void)argc;
+//    int action = ACTION_RUN;
+    size_t nthreads = 1;
+
+    struct optparse opts;
+    optparse_init(&opts, argv);
+    int opt;
+
+    while ((opt = optparse(&opts, "j:s")) != -1) {
+        switch (opt) {
+        case 'j':
+            nthreads = strtoul(opts.optarg, NULL, 0);
+            break;
+        case 's':
+            silent_success = 0;
+            break;
+        default:
+            fprintf(stderr, "[!] Unknown option: '%c'\n", opt);
+            exit(1);
+        }
+    }
+
+
+    DIR *cwd = opendir(".");
+    pthread_t *threads = malloc(sizeof(pthread_t)*nthreads);
+    for (size_t i = 0; i < nthreads; i++) {
+        pthread_create(threads + i, NULL, thread_run_test, cwd);
+    }
+    for (size_t i = 0; i < nthreads; i++) {
+        void *retval;
+        pthread_join(threads[i], &retval);
+    }
+    free(threads);
+    return 0;
+}