diff --git a/tests/unittests/CMakeLists.txt b/tests/unittests/CMakeLists.txt
index f1459865..04fcba11 100644
--- a/tests/unittests/CMakeLists.txt
+++ b/tests/unittests/CMakeLists.txt
@@ -3,6 +3,7 @@ project(unittests C)
 include_directories(${OPENSSL_INCLUDE_DIR})
 
 set(LIBSSH_UNIT_TESTS
+    torture_bignum
     torture_buffer
     torture_bytearray
     torture_callbacks
diff --git a/tests/unittests/torture_bignum.c b/tests/unittests/torture_bignum.c
new file mode 100644
index 00000000..c36b81f8
--- /dev/null
+++ b/tests/unittests/torture_bignum.c
@@ -0,0 +1,106 @@
+#include "config.h"
+
+#define LIBSSH_STATIC
+
+#include "torture.h"
+#include "libssh/bignum.h"
+#include "libssh/string.h"
+
+static void check_str (int n, ssh_string str)
+{
+    if (n > 0 && n <= 127) {
+        assert_int_equal(1, ntohl (str->size));
+        assert_int_equal(n, str->data[0]);
+    } else if (n > 127 && n <= 255) {
+        assert_int_equal(2, ntohl (str->size));
+        assert_int_equal(0, str->data[0]);
+        assert_int_equal(n, str->data[1]);
+    } else if (n > 255 && n <= 32767) {
+        assert_int_equal(2, ntohl (str->size));
+        assert_int_equal(n >> 8, str->data[0]);
+        assert_int_equal(n & 0xFF, str->data[1]);
+    } else {
+        assert_int_equal(3, ntohl (str->size));
+        assert_int_equal(n >> 16, str->data[0]);
+        assert_int_equal((n >> 8) & 0xFF, str->data[1]);
+        assert_int_equal(n & 0xFF, str->data[2]);
+    }
+}
+
+static void check_bignum(int n, const char *nstr) {
+    bignum num, num2;
+    ssh_string str;
+    char *dec;
+
+    num = bignum_new();
+    assert_non_null(num);
+
+    assert_int_equal (1, bignum_set_word (num, n));
+
+    ssh_print_bignum("num", num);
+
+    dec = bignum_bn2dec (num);
+    assert_non_null (dec);
+    assert_string_equal (nstr, dec);
+    ssh_crypto_free(dec);
+
+    /* ssh_make_bignum_string */
+
+    str = ssh_make_bignum_string(num);
+    assert_non_null(str);
+
+    check_str (n, str);
+
+    /* ssh_make_string_bn */
+
+    num2 = ssh_make_string_bn(str);
+    ssh_string_free (str);
+    assert_non_null(num2);
+
+    ssh_print_bignum("num2", num2);
+
+    assert_int_equal (0, bignum_cmp (num, num2));
+
+    dec = bignum_bn2dec (num2);
+    assert_non_null (dec);
+    assert_string_equal (nstr, dec);
+    ssh_crypto_free(dec);
+
+    bignum_safe_free(num);
+    bignum_safe_free(num2);
+}
+
+
+static void torture_bignum(void **state) {
+    (void) state; /* unused */
+
+    ssh_set_log_level(SSH_LOG_TRACE);
+
+    check_bignum (1, "1");
+    check_bignum (17, "17");
+    check_bignum (42, "42");
+    check_bignum (127, "127");
+    check_bignum (128, "128");
+    check_bignum (254, "254");
+    check_bignum (255, "255");
+    check_bignum (256, "256");
+    check_bignum (257, "257");
+    check_bignum (300, "300");
+    check_bignum (32767, "32767");
+    check_bignum (32768, "32768");
+    check_bignum (65535, "65535");
+    check_bignum (65536, "65536");
+}
+
+int torture_run_tests(void) {
+    int rc;
+    struct CMUnitTest tests[] = {
+        cmocka_unit_test(torture_bignum),
+    };
+
+    ssh_init();
+    torture_filter_tests(tests);
+    rc = cmocka_run_group_tests(tests, NULL, NULL);
+    ssh_finalize();
+    return rc;
+}