diff --git a/unitTests/CMakeLists.txt b/unitTests/CMakeLists.txt
index 57b59e85..51040c0e 100644
--- a/unitTests/CMakeLists.txt
+++ b/unitTests/CMakeLists.txt
@@ -62,8 +62,7 @@ if( EXIV2_ENABLE_PNG )
 endif()
 
 target_include_directories(unit_tests
-    PRIVATE
-        ${CMAKE_SOURCE_DIR}/src
+    PRIVATE ${PROJECT_SOURCE_DIR}/src
 )
 
 set_target_properties(unit_tests PROPERTIES