diff --git a/tools/pybind11Tools.cmake b/tools/pybind11Tools.cmake
index 52a70c2..1e9d033 100644
--- a/tools/pybind11Tools.cmake
+++ b/tools/pybind11Tools.cmake
@@ -130,7 +130,7 @@ function(pybind11_add_module target_name)
 
   add_library(${target_name} ${lib_type} ${exclude_from_all} ${ARG_UNPARSED_ARGUMENTS})
 
-  target_include_directories(${target_name}
+  target_include_directories(${target_name} SYSTEM
     PRIVATE ${PYBIND11_INCLUDE_DIR}  # from project CMakeLists.txt
     PRIVATE ${pybind11_INCLUDE_DIR}  # from pybind11Config
     PRIVATE ${PYTHON_INCLUDE_DIRS})