diff --git a/ports/zephyr/CMakeLists.txt b/ports/zephyr/CMakeLists.txt
index a5cc477204..e7a55d804a 100644
--- a/ports/zephyr/CMakeLists.txt
+++ b/ports/zephyr/CMakeLists.txt
@@ -30,6 +30,7 @@ project(micropython)
 set(MICROPY_PORT_DIR    ${CMAKE_CURRENT_SOURCE_DIR})
 set(MICROPY_DIR         ${MICROPY_PORT_DIR}/../..)
 set(MICROPY_TARGET      micropython)
+string(TOUPPER          ZEPHYR_${BOARD} MICROPY_BOARD)
 
 include(${MICROPY_DIR}/py/py.cmake)
 include(${MICROPY_DIR}/extmod/extmod.cmake)