diff --git a/conf/boards/booz_1.0.makefile b/conf/boards/booz_1.0.makefile
index 7e9184cf5c..7df1cf8039 100644
--- a/conf/boards/booz_1.0.makefile
+++ b/conf/boards/booz_1.0.makefile
@@ -25,8 +25,12 @@ RADIO_CONTROL_LINK = UART0
 
 BARO_LED = 2
 
+ifndef MODEM_PORT
 MODEM_PORT = UART1
+endif
+ifndef MODEM_BAUD
 MODEM_BAUD = B57600
+endif
 
 AHRS_ALIGNER_LED = 3
 
diff --git a/conf/boards/hb_1.1.makefile b/conf/boards/hb_1.1.makefile
index 16c134efc5..382653cdda 100644
--- a/conf/boards/hb_1.1.makefile
+++ b/conf/boards/hb_1.1.makefile
@@ -22,8 +22,12 @@ SYS_TIME_LED = 1 # not used on rotorcraft, only for tests
 
 RADIO_CONTROL_LINK = UART0
 
+ifndef MODEM_PORT
 MODEM_PORT = UART0
+endif
+ifndef MODEM_BAUD
 MODEM_BAUD = B57600
+endif
 
 GPS_PORT=UART1
 GPS_BAUD=B38400
diff --git a/conf/boards/lisa_l_1.0.makefile b/conf/boards/lisa_l_1.0.makefile
index a821a51298..84a27aab63 100644
--- a/conf/boards/lisa_l_1.0.makefile
+++ b/conf/boards/lisa_l_1.0.makefile
@@ -41,8 +41,12 @@ RADIO_CONTROL_SPEKTRUM_PRIMARY_PORT   = UART3
 RADIO_CONTROL_SPEKTRUM_SECONDARY_PORT = UART5
 RADIO_CONTROL_LED  = 5
 
+ifndef MODEM_PORT
 MODEM_PORT=UART2
+endif
+ifndef MODEM_BAUD
 MODEM_BAUD=B57600
+endif
 
 AHRS_ALIGNER_LED = 7