diff --git a/ports/stm32f4/mpconfigport.mk b/ports/stm32f4/mpconfigport.mk
index 5f697e5a98..e814d86e43 100644
--- a/ports/stm32f4/mpconfigport.mk
+++ b/ports/stm32f4/mpconfigport.mk
@@ -21,7 +21,7 @@ CIRCUITPY_ANALOGIO = 1
 CIRCUITPY_MICROCONTROLLER = 1
 CIRCUITPY_BUSIO = 1
 CIRCUITPY_TIME = 1
-CIRCUITPY_BUSIO = 1
+CIRCUITPY_OS = 1
 CIRCUITPY_STRUCT = 1
 
 #ifeq ($(MCU_SUB_VARIANT), stm32f412zx)