diff --git a/lab04/lab04.cpp b/lab04/lab04.cpp
new file mode 100644
index 0000000..315510a
--- /dev/null
+++ b/lab04/lab04.cpp
@@ -0,0 +1,20 @@
+#include <cassert>
+#include <iostream>
+using namespace std;
+
+char nibble_to_hex(uint8_t i) {
+    assert(0x0 <= i && i <= 0xf);
+    if (i < 10) return '0' + i;
+    return 'a' + (i - 10);
+}
+
+void test_nibble_to_hex() {
+    assert(nibble_to_hex(0x0) == '0');
+    assert(nibble_to_hex(0xf) == 'f');
+    cout << "nibble_to_hex() tests passed!\n";
+}
+
+int main() {
+    test_nibble_to_hex();
+    return 0;
+}