diff --git a/sw/airborne/arch/lpc21/mcu_periph/i2c_arch.c b/sw/airborne/arch/lpc21/mcu_periph/i2c_arch.c
index 11c51bbaecd..98f65140a99 100644
--- a/sw/airborne/arch/lpc21/mcu_periph/i2c_arch.c
+++ b/sw/airborne/arch/lpc21/mcu_periph/i2c_arch.c
@@ -270,6 +270,11 @@ void i2c0_hw_init ( void ) {
 #endif
 #endif
 
+#ifndef I2C1_VIC_SLOT
+#define I2C1_VIC_SLOT 11
+#endif
+
+
 void i2c1_ISR(void) __attribute__((naked));
 
 void i2c1_ISR(void) {
diff --git a/sw/airborne/arch/lpc21/vic_slots_fw.txt b/sw/airborne/arch/lpc21/vic_slots_fw.txt
index 6c94aa7bfe4..86f238d5a80 100644
--- a/sw/airborne/arch/lpc21/vic_slots_fw.txt
+++ b/sw/airborne/arch/lpc21/vic_slots_fw.txt
@@ -17,6 +17,7 @@ SSP_VIC_SLOT               9          imu_b2_v1.0, imu_b2_v1.1, imu_b2_v1.2
 MICROMAG_DRDY_VIC_SLOT     9          micromag
 hardcoded, no define      10          usb, e.g. telemetry_transparent_usb
 hardcoded, no define      11          EXTINT in baro_scp module
+I2C1_VIC_SLOT              ? (11)     (11 is default in mcu_periph/i2c_arch.c)
 I2C1_VIC_SLOT             12          ami601 in imu_b2_v1.0, imu_crista
 MS2100_DRDY_VIC_SLOT      12          ms2100 mag in imu_b2_v1.1
 MAX11040_DRDY_VIC_SLOT     ?          max11040 adc module