diff --git a/unittests/timemanager/TestCountdown.cpp b/unittests/timemanager/TestCountdown.cpp
index 67f4ddb2..61d372e7 100644
--- a/unittests/timemanager/TestCountdown.cpp
+++ b/unittests/timemanager/TestCountdown.cpp
@@ -1,15 +1,18 @@
 #include <fsfw/timemanager/Countdown.h>
 
 #include <catch2/catch_test_macros.hpp>
+#include <chrono>
+#include <thread>
 
 #include "CatchDefinitions.h"
 
+static constexpr bool TEST_LONGER_CD = false;
 TEST_CASE("Countdown Tests", "[TestCountdown]") {
   INFO("Countdown Tests");
   Countdown count(20);
-  REQUIRE(count.timeout == 20);
+  REQUIRE(count.getTimeoutMs() == 20);
   REQUIRE(count.setTimeout(100) == static_cast<uint16_t>(returnvalue::OK));
-  REQUIRE(count.timeout == 100);
+  REQUIRE(count.getTimeoutMs() == 100);
   REQUIRE(count.setTimeout(150) == static_cast<uint16_t>(returnvalue::OK));
   REQUIRE(count.isBusy());
   REQUIRE(not count.hasTimedOut());
@@ -25,4 +28,19 @@ TEST_CASE("Countdown Tests", "[TestCountdown]") {
   count.resetTimer();
   REQUIRE(not count.hasTimedOut());
   REQUIRE(count.isBusy());
+  count.setTimeout(100);
+  REQUIRE(not count.hasTimedOut());
+  std::this_thread::sleep_for(std::chrono::milliseconds(50));
+  REQUIRE(not count.hasTimedOut());
+  std::this_thread::sleep_for(std::chrono::milliseconds(50));
+  REQUIRE(count.hasTimedOut());
+
+  // Takes longer, disabled by default
+  if (TEST_LONGER_CD) {
+    count.setTimeout(2500);
+    std::this_thread::sleep_for(std::chrono::milliseconds(1000));
+    REQUIRE(not count.hasTimedOut());
+    std::this_thread::sleep_for(std::chrono::milliseconds(1500));
+    REQUIRE(count.hasTimedOut());
+  }
 }