diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index c4e1bb6..4651296 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -50,6 +50,7 @@ if(GMIO_BUILD_SHARED_LIBS)
     #         exports all symbols)
     set(GMIO_TEST_CORE_SRC
             ${GMIO_TEST_CORE_SRC}
+            ../src/gmio_core/internal/locale_utils.c
             ../src/gmio_core/internal/numeric_utils.c
             ../src/gmio_core/internal/stringstream.c)
 endif()
@@ -69,6 +70,7 @@ if(GMIO_BUILD_SHARED_LIBS)
     # See Note_1
     set(GMIO_TEST_STL_SRC
             ${GMIO_TEST_STL_SRC}
+            ../src/gmio_core/internal/locale_utils.c
             ../src/gmio_core/internal/numeric_utils.c
             ../src/gmio_stl/internal/stl_rw_common.c)
 endif()