diff --git a/conf/airframes/examples/quadrotor_lisa_m_2_pwm_spektrum.xml b/conf/airframes/examples/quadrotor_lisa_m_2_pwm_spektrum.xml
index e133cef851..31fcbbc351 100644
--- a/conf/airframes/examples/quadrotor_lisa_m_2_pwm_spektrum.xml
+++ b/conf/airframes/examples/quadrotor_lisa_m_2_pwm_spektrum.xml
@@ -25,6 +25,7 @@
 
     <subsystem name="actuators"     type="pwm_supervision">
       <define name="SERVO_HZ" value="400"/>
+      <define name="USE_SERVOS_7AND8"/>
     </subsystem>
 
     <subsystem name="telemetry"     type="transparent"/>
diff --git a/sw/airborne/firmwares/rotorcraft/actuators/arch/stm32/actuators_pwm_arch.h b/sw/airborne/firmwares/rotorcraft/actuators/arch/stm32/actuators_pwm_arch.h
index 480dd466c6..2117fdded1 100644
--- a/sw/airborne/firmwares/rotorcraft/actuators/arch/stm32/actuators_pwm_arch.h
+++ b/sw/airborne/firmwares/rotorcraft/actuators/arch/stm32/actuators_pwm_arch.h
@@ -27,7 +27,11 @@
 #define ACTUATORS_PWM_ARCH_H
 
 #if USE_SERVOS_7AND8
+#if defined(BOARD_LISA_M) && USE_I2C1
+#error "You cannot use Servos 7and8 and I2C1 at the same time"
+#else
 #define ACTUATORS_PWM_NB 8
+#endif
 #else
 #define ACTUATORS_PWM_NB 6
 #endif