diff --git a/sw/airborne/arch/stm32/subsystems/radio_control/spektrum_arch.c b/sw/airborne/arch/stm32/subsystems/radio_control/spektrum_arch.c
index 91b609b63d..583b90c089 100644
--- a/sw/airborne/arch/stm32/subsystems/radio_control/spektrum_arch.c
+++ b/sw/airborne/arch/stm32/subsystems/radio_control/spektrum_arch.c
@@ -85,7 +85,10 @@ typedef struct SpektrumStateStruct SpektrumStateType;
 
 SpektrumStateType PrimarySpektrumState = {1,0,0,0,0,0,0,0,0};
 #ifdef RADIO_CONTROL_SPEKTRUM_SECONDARY_PORT
+#warning "Using secondary spektrum receiver."
 SpektrumStateType SecondarySpektrumState = {1,0,0,0,0,0,0,0,0};
+#else
+#warning "NOT using secondary spektrum receiver."
 #endif
 
 int16_t SpektrumBuf[SPEKTRUM_CHANNELS_PER_FRAME*MAX_SPEKTRUM_FRAMES];