diff --git a/ports/stm32/mboot/Makefile b/ports/stm32/mboot/Makefile
index 7e1b497cef63..20b0db9070cd 100755
--- a/ports/stm32/mboot/Makefile
+++ b/ports/stm32/mboot/Makefile
@@ -162,6 +162,7 @@ SRC_HAL += $(addprefix $(HAL_DIR)/Src/stm32$(MCU_SERIES)xx_,\
 	hal_pcd.c \
 	hal_pcd_ex.c \
 	hal_rcc.c \
+	hal_rcc_ex.c \
 	ll_usb.c \
 	)