diff --git a/src/systems/CMakeLists.txt b/src/systems/CMakeLists.txt
index 8e431e40a44..7b0f7c24693 100644
--- a/src/systems/CMakeLists.txt
+++ b/src/systems/CMakeLists.txt
@@ -21,7 +21,7 @@ function(gz_add_system system_name)
 
   set(options)
   set(oneValueArgs)
-  set(multiValueArgs SOURCES PUBLIC_LINK_LIBS PRIVATE_LINK_LIBS PRIVATE_COMPILE_DEFS)
+  set(multiValueArgs SOURCES PUBLIC_LINK_LIBS PRIVATE_INCLUDE_DIRS PRIVATE_LINK_LIBS PRIVATE_COMPILE_DEFS)
 
   cmake_parse_arguments(gz_add_system "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
@@ -47,6 +47,13 @@ function(gz_add_system system_name)
       ignition-plugin${IGN_PLUGIN_VER}::register
   )
 
+  if(gz_add_system_PRIVATE_INCLUDE_DIRS)
+    target_include_directories(${system_target}
+      PRIVATE
+        ${gz_add_system_PRIVATE_INCLUDE_DIRS}
+    )
+  endif()
+
   if(gz_add_system_PRIVATE_COMPILE_DEFS)
     target_compile_definitions(${system_target}
       PRIVATE