diff --git a/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk b/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk
index 76acd7ed1e..211a658967 100644
--- a/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk
+++ b/ports/stm/boards/stm32f411ce_blackpill_with_flash/mpconfigboard.mk
@@ -16,3 +16,5 @@ MCU_PACKAGE = UFQFPN48
 
 LD_COMMON = boards/common_default.ld
 LD_FILE = boards/STM32F411_nvm_nofs.ld
+
+CIRCUITPY_SYNTHIO = 0