diff --git a/test/add-subdirectory-test/CMakeLists.txt b/test/add-subdirectory-test/CMakeLists.txt
index 6c92299..0fd6821 100644
--- a/test/add-subdirectory-test/CMakeLists.txt
+++ b/test/add-subdirectory-test/CMakeLists.txt
@@ -7,5 +7,5 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 
 add_subdirectory(../.. cxxopts EXCLUDE_FROM_ALL)
 
-add_executable(library-test "../../src/example.cpp")
+add_executable(library-test "${PROJECT_SOURCE_DIR}/src/example.cpp")
 target_link_libraries(library-test cxxopts)