diff --git a/score/mw/com/dependability/requirements/component_requirements/BUILD b/score/mw/com/dependability/requirements/component_requirements/BUILD
index 3e790a0386..23d04c61df 100644
--- a/score/mw/com/dependability/requirements/component_requirements/BUILD
+++ b/score/mw/com/dependability/requirements/component_requirements/BUILD
@@ -45,6 +45,7 @@ component_requirements(
     deps = [
         "//score/mw/com/dependability/assumed_system:assumed_system_requirements",
         "//score/mw/com/dependability/requirements/feature_requirements:feature_requirements_ipc",
+        "//score/mw/com/dependability/safety_analysis:mw_com_safety_analysis",
     ],
 )
 
diff --git a/score/mw/com/dependability/requirements/component_requirements/component_requirements_ipc.trlc b/score/mw/com/dependability/requirements/component_requirements/component_requirements_ipc.trlc
index 82101ff9ce..80a785a9ec 100644
--- a/score/mw/com/dependability/requirements/component_requirements/component_requirements_ipc.trlc
+++ b/score/mw/com/dependability/requirements/component_requirements/component_requirements_ipc.trlc
@@ -13,6 +13,7 @@
 package Communication
 
 import ScoreReq
+import mw_com_fta
 
 section "com" {
 
@@ -761,7 +762,7 @@ section "com" {
 
             * Each destruction or {{nullptr\_t}} assignment of a SamplePtr instance created from this Event class instance shall lead to a increment of count of free samples.'''
             safety = ScoreReq.Asil.B
-            derived_from = [Communication.FEAT_SupportForTimeBasedArchitecture@2]
+            derived_from = [Communication.FEAT_SupportForTimeBasedArchitecture@2, mw_com_fta.RootCauseReturnsWrongFreeSampleCount]
             version = 1
         }
 
diff --git a/score/mw/com/impl/proxy_event_test.cpp b/score/mw/com/impl/proxy_event_test.cpp
index a915afb169..9e35137b7a 100644
--- a/score/mw/com/impl/proxy_event_test.cpp
+++ b/score/mw/com/impl/proxy_event_test.cpp
@@ -175,6 +175,7 @@ TYPED_TEST(ProxyEventFixture, SamplePtrLimitsAreEnforced)
     Base::RecordProperty(
         "Verifies",
         "SCR-6367376, SCR-6342893, SCR-6225130, SCR-6338237, SCR-6340966, SCR-14035773, SCR-21350367, SCR-21803116");
+    Base::RecordProperty("lobster-tracing", "Communication.CalculationOfFreeSampleCount");
     Base::RecordProperty("Description",
                          "Checks event proxy by simulating an skeleton event. Also checks that GetFreeSampleCount "
                          "correctly reflects the number of samples that can be received by the user.");
@@ -239,6 +240,51 @@ TYPED_TEST(ProxyEventFixture, SamplePtrLimitsAreEnforced)
     EXPECT_EQ(num_callback_calls, *get_result_2);
 }
 
+TYPED_TEST(ProxyEventFixture, AssigningNullptrToSamplePtrIncrementsFreeSampleCount)
+{
+    using Base = ProxyEventFixture<TypeParam>;
+
+    Base::RecordProperty("Verifies", "SCR-21803116");
+    Base::RecordProperty("lobster-tracing", "Communication.CalculationOfFreeSampleCount");
+    Base::RecordProperty("Description",
+                         "Checks that assigning nullptr to a SamplePtr obtained via GetNewSamples increments the free "
+                         "sample count, while the SamplePtr being held keeps it decremented.");
+    Base::RecordProperty("TestType", "Requirements-based test");
+    Base::RecordProperty("Priority", "1");
+    Base::RecordProperty("DerivationTechnique", "Analysis of requirements");
+
+    const std::size_t max_num_samples{2U};
+
+    EXPECT_CALL(Base::mock_proxy_event_, GetSubscriptionState())
+        .WillOnce(::testing::Return(SubscriptionState::kNotSubscribed));
+    EXPECT_CALL(Base::mock_proxy_event_, Subscribe(max_num_samples));
+    EXPECT_CALL(Base::mock_proxy_event_, GetNewSamples(_, _)).Times(1);
+
+    // Given a subscribed proxy event with max_num_samples free samples
+    std::ignore = Base::proxy_event_.Subscribe(max_num_samples);
+    EXPECT_EQ(Base::proxy_event_.GetFreeSampleCount(), max_num_samples);
+
+    // and one sample received and held by the user
+    Base::mock_proxy_event_.PushFakeSample(42U);
+    SamplePtr<typename Base::SampleType> held_sample{};
+    const auto get_result = Base::proxy_event_.GetNewSamples(
+        [&held_sample](SamplePtr<typename Base::SampleType> ptr) {
+            held_sample = std::move(ptr);
+        },
+        1U);
+    ASSERT_TRUE(get_result.has_value());
+    ASSERT_EQ(*get_result, 1U);
+
+    // Then the free sample count is decremented
+    EXPECT_EQ(Base::proxy_event_.GetFreeSampleCount(), max_num_samples - 1U);
+
+    // When nullptr is assigned to the SamplePtr
+    held_sample = nullptr;
+
+    // Then the free sample count is incremented again
+    EXPECT_EQ(Base::proxy_event_.GetFreeSampleCount(), max_num_samples);
+}
+
 template <typename T>
 using ProxyEventDeathTest = ProxyEventFixture<T>;
 TYPED_TEST_SUITE(ProxyEventDeathTest, MyTypes, );