diff --git a/lab04/lab04.cpp b/lab04/lab04.cpp
index 315510a..cc4e256 100644
--- a/lab04/lab04.cpp
+++ b/lab04/lab04.cpp
@@ -14,7 +14,22 @@ void test_nibble_to_hex() {
     cout << "nibble_to_hex() tests passed!\n";
 }
 
+uint8_t low_nibble(uint8_t byte) {
+    return byte & 0x0f;
+}
+
+uint8_t high_nibble(uint8_t byte) {
+    return byte >> 4;
+}
+
+void test_nibbles() {
+    assert(low_nibble(0xab) == 0xb);
+    assert(high_nibble(0xab) == 0xa);
+    cout << "Nibble extraction tests passed!\n";
+}
+
 int main() {
     test_nibble_to_hex();
+    test_nibbles();
     return 0;
 }