diff --git a/tests/src/Base/Bitmask.cpp b/tests/src/Base/Bitmask.cpp
new file mode 100644
index 0000000000..1c64180efb
--- /dev/null
+++ b/tests/src/Base/Bitmask.cpp
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#include "gtest/gtest.h"
+
+#include <Base/Bitmask.h>
+
+enum class TestFlagEnum {
+    Flag1,
+    Flag2,
+    Flag3
+};
+
+class BitmaskTest: public ::testing::Test
+{
+protected:
+    // void SetUp() override {};
+    // void TearDown() override {};
+};
+
+TEST_F(BitmaskTest, toUnderlyingType)
+{
+    // Arrange
+    Base::Flags<TestFlagEnum> flag1 {TestFlagEnum::Flag1};
+
+    // Act
+    auto result = flag1.toUnderlyingType();
+
+    // Assert
+    EXPECT_EQ(typeid(result), typeid(int));
+}
diff --git a/tests/src/Base/CMakeLists.txt b/tests/src/Base/CMakeLists.txt
index 638c5a1fad..6871874838 100644
--- a/tests/src/Base/CMakeLists.txt
+++ b/tests/src/Base/CMakeLists.txt
@@ -1,6 +1,7 @@
 target_sources(
     Tests_run
         PRIVATE
+            ${CMAKE_CURRENT_SOURCE_DIR}/Bitmask.cpp
             ${CMAKE_CURRENT_SOURCE_DIR}/Matrix.cpp
             ${CMAKE_CURRENT_SOURCE_DIR}/Quantity.cpp
             ${CMAKE_CURRENT_SOURCE_DIR}/Reader.cpp