diff --git a/tests/unit_tests/openvpn/test_buffer.c b/tests/unit_tests/openvpn/test_buffer.c
index 5f43e0d..326de40 100644
--- a/tests/unit_tests/openvpn/test_buffer.c
+++ b/tests/unit_tests/openvpn/test_buffer.c
@@ -460,6 +460,32 @@
     gc_free(&gc);
 }
 
+void
+test_buffer_null_terminate(void **state)
+{
+    struct gc_arena gc = gc_new();
+
+    struct buffer buf = alloc_buf_gc(5, &gc);
+    const char test1[] = "1234";
+    const char test2[] = "12345";
+    assert_true(buf_write(&buf, test1, sizeof(test1)));
+    assert_string_equal(BSTR(&buf), "1234");
+    buf_null_terminate(&buf);
+    assert_string_equal(BSTR(&buf), "1234");
+
+    assert_true(buf_inc_len(&buf, -1));
+    assert_true(buf_write_u8(&buf, '5'));
+    assert_memory_equal(BPTR(&buf), test2, strlen(test2));
+    buf_null_terminate(&buf);
+    assert_string_equal(BSTR(&buf), "1234");
+
+    struct buffer buf2;
+    CLEAR(buf2);
+    buf_null_terminate(&buf2);
+
+    gc_free(&gc);
+}
+
 /* for building long texts */
 #define A_TIMES_256 "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAO"
 
@@ -540,6 +566,7 @@
         cmocka_unit_test(test_snprintf),
         cmocka_unit_test(test_checked_snprintf),
         cmocka_unit_test(test_buffer_chomp),
+        cmocka_unit_test(test_buffer_null_terminate),
         cmocka_unit_test(test_buffer_parse)
     };