diff --git a/Fit/CMakeLists.txt b/Fit/CMakeLists.txt
index bf8f254163af8df010f5e6cee9f9e67d93914216..fec01a45a33b9ac1580fdb7bfc68fdefe373b623 100644
--- a/Fit/CMakeLists.txt
+++ b/Fit/CMakeLists.txt
@@ -27,8 +27,9 @@ target_link_libraries(${lib}
 target_include_directories(${lib}
     PUBLIC
     ${CMAKE_SOURCE_DIR}
-    SYSTEM PUBLIC # because needed by Fit/Test/Unit
-    ${Boost_INCLUDE_DIRS}
+    SYSTEM PUBLIC
+    ${LibHeinz_INCLUDE_DIR}
+    ${Boost_INCLUDE_DIRS}  # because needed by Fit/Test/Unit ?
     SYSTEM PRIVATE
     ${RootMinimizers_INCLUDE_DIRS}
     )