diff --git a/tools/toolchain.cmake.export b/tools/toolchain.cmake.export
index b943f217c06..c879954df0a 100644
--- a/tools/toolchain.cmake.export
+++ b/tools/toolchain.cmake.export
@@ -1,5 +1,6 @@
 set(CMAKE_SYSTEM_NAME Generic)
 set(CMAKE_SYSTEM_VERSION 1)
+set(NUTTX 1)
 
 set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)