diff --git a/conf/firmwares/setup.makefile b/conf/firmwares/setup.makefile
index c234518ab4..7cf27a2132 100644
--- a/conf/firmwares/setup.makefile
+++ b/conf/firmwares/setup.makefile
@@ -108,7 +108,7 @@ setup_actuators.srcs   += mcu_periph/uart.c $(SRC_ARCH)/mcu_periph/uart_arch.c
 setup_actuators.CFLAGS += -DUSE_$(MODEM_PORT)
 setup_actuators.CFLAGS += -D$(MODEM_PORT)_BAUD=$(MODEM_BAUD)
 SETUP_ACTUATORS_MODEM_PORT_LOWER=$(shell echo $(MODEM_PORT) | tr A-Z a-z)
-setup_actuators.CFLAGS += -DDOWNLINK -DDOWNLINK_DEVICE=$(SETUP_ACTUATORS_MODEM_PORT_LOWER) -DPPRZ_UART=$(MODEM_PORT)
+setup_actuators.CFLAGS += -DDOWNLINK -DDOWNLINK_DEVICE=$(SETUP_ACTUATORS_MODEM_PORT_LOWER) -DPPRZ_UART=$(SETUP_ACTUATORS_MODEM_PORT_LOWER)
 setup_actuators.CFLAGS += -DDOWNLINK_TRANSPORT=pprz_tp -DDATALINK=PPRZ
 setup_actuators.srcs += subsystems/datalink/downlink.c subsystems/datalink/pprz_transport.c
 
diff --git a/conf/firmwares/test_progs.makefile b/conf/firmwares/test_progs.makefile
index 7ae2ccf827..335d4bdd3a 100644
--- a/conf/firmwares/test_progs.makefile
+++ b/conf/firmwares/test_progs.makefile
@@ -82,7 +82,7 @@ UDP_MODEM_PORT_LOWER=$(shell echo $(MODEM_DEV) | tr A-Z a-z)
 
 COMMON_TELEMETRY_CFLAGS += -DUSE_$(MODEM_DEV) -D$(MODEM_DEV)_PORT_OUT=$(MODEM_PORT_OUT) -D$(MODEM_DEV)_PORT_IN=$(MODEM_PORT_IN)
 COMMON_TELEMETRY_CFLAGS += -D$(MODEM_DEV)_BROADCAST=$(MODEM_BROADCAST) -D$(MODEM_DEV)_HOST=\"$(MODEM_HOST)\"
-COMMON_TELEMETRY_CFLAGS += -DPPRZ_UART=$(MODEM_DEV)
+COMMON_TELEMETRY_CFLAGS += -DPPRZ_UART=$(UDP_MODEM_PORT_LOWER)
 COMMON_TELEMETRY_CFLAGS += -DDOWNLINK_DEVICE=$(UDP_MODEM_PORT_LOWER)
 else
 # via UART
@@ -91,7 +91,7 @@ else
 #endif
 COMMON_TELEMETRY_MODEM_PORT_LOWER=$(shell echo $(MODEM_PORT) | tr A-Z a-z)
 COMMON_TELEMETRY_CFLAGS += -DUSE_$(MODEM_PORT) -D$(MODEM_PORT)_BAUD=$(MODEM_BAUD)
-COMMON_TELEMETRY_CFLAGS += -DPPRZ_UART=$(MODEM_PORT)
+COMMON_TELEMETRY_CFLAGS += -DPPRZ_UART=$(COMMON_TELEMETRY_MODEM_PORT_LOWER)
 COMMON_TELEMETRY_CFLAGS += -DDOWNLINK_DEVICE=$(COMMON_TELEMETRY_MODEM_PORT_LOWER)
 COMMON_TELEMETRY_SRCS  += mcu_periph/uart.c
 COMMON_TELEMETRY_SRCS  += $(SRC_ARCH)/mcu_periph/uart_arch.c