diff --git a/phlex/app/CMakeLists.txt b/phlex/app/CMakeLists.txt
index b812aef9..b9482f98 100644
--- a/phlex/app/CMakeLists.txt
+++ b/phlex/app/CMakeLists.txt
@@ -5,7 +5,7 @@ add_library(version_obj OBJECT version.cpp)
 # version.cpp is generated into the build directory; clang-tidy cannot find
 # .clang-tidy by walking the build-dir path, so disable linting for this file.
 set_target_properties(version_obj PROPERTIES CXX_CLANG_TIDY "" POSITION_INDEPENDENT_CODE TRUE)
-target_include_directories(version_obj PRIVATE ${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR}/include)
+target_include_directories(version_obj PRIVATE ${PROJECT_SOURCE_DIR} ${CMAKE_BINARY_DIR}/include)
 
 cet_make_library(
   LIBRARY_NAME