diff --git a/tests/module_cpp20/CMakeLists.txt b/tests/module_cpp20/CMakeLists.txt
index c628bdb5c..b6d395aaa 100644
--- a/tests/module_cpp20/CMakeLists.txt
+++ b/tests/module_cpp20/CMakeLists.txt
@@ -4,7 +4,7 @@ project(json_test CXX)
 
 set(NLOHMANN_JSON_BUILD_MODULES ON CACHE BOOL "Enable nlohmann.json module support")
 
-add_subdirectory(${CMAKE_SOURCE_DIR}/../.. ${CMAKE_BINARY_DIR}/tests)
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/../.. ${CMAKE_CURRENT_BINARY_DIR}/tests)
 
 add_executable(json_test main.cpp)
 target_link_libraries(json_test