diff --git a/cmake/KF5I18nMacros.cmake.in b/cmake/KF5I18nMacros.cmake.in
--- a/cmake/KF5I18nMacros.cmake.in
+++ b/cmake/KF5I18nMacros.cmake.in
@@ -68,7 +68,12 @@
          MAIN_DEPENDENCY ${_tmp_FILE}
       )
       set_source_files_properties(${_header} PROPERTIES SKIP_AUTOMOC ON)
-      list(APPEND ${_sources} ${_header})
+      if(TARGET ${_sources})
+         cmake_minimum_required(VERSION 3.1)
+         target_sources(${_sources} PRIVATE ${_header})
+      else()
+         list(APPEND ${_sources} ${_header})
+      endif()
    endforeach (_current_FILE)
 endmacro (KI18N_WRAP_UI)