diff --git a/src/platforms/px4_micro_hal.h b/src/platforms/px4_micro_hal.h
index e50deaad1f..cd2e4ce5dd 100644
--- a/src/platforms/px4_micro_hal.h
+++ b/src/platforms/px4_micro_hal.h
@@ -48,12 +48,14 @@ __BEGIN_DECLS
 #      define PX4_BBSRAM_SIZE STM32_BBSRAM_SIZE
 #      define PX4_BBSRAM_GETDESC_IOCTL STM32_BBSRAM_GETDESC_IOCTL
 #      define PX4_FLASH_BASE  STM32_FLASH_BASE
+#      define PX4_NUMBER_I2C_BUSES STM32_NI2C
 #    endif
 #    if defined(CONFIG_ARCH_CHIP_STM32F7)
 #      include <chip.h>
 #      define PX4_BBSRAM_SIZE STM32F7_BBSRAM_SIZE
 #      define PX4_BBSRAM_GETDESC_IOCTL STM32F7_BBSRAM_GETDESC_IOCTL
 #      define PX4_FLASH_BASE  0x08000000
+#      define PX4_NUMBER_I2C_BUSES STM32F7_NI2C
 #    endif
 #    include <stm32_tim.h>
 #    include <stm32_spi.h>