diff --git a/lambda-test/Makefile b/lambda-test/Makefile
index 7f1da67..dfca381 100644
--- a/lambda-test/Makefile
+++ b/lambda-test/Makefile
@@ -31,7 +31,7 @@
 
 PROGRAMMER_TYPE = avrisp
 # extra arguments to avrdude: baud rate, chip type, -F flag, etc.
-PROGRAMMER_ARGS = -b 19200 -P /dev/ttyACM0
+PROGRAMMER_ARGS = -b 19200 -P /dev/ttyACM3
 
 ##########------------------------------------------------------##########
 ##########                   Makefile Magic!                    ##########
diff --git a/lambda/Makefile b/lambda/Makefile
index b34ace8..ef23aad 100644
--- a/lambda/Makefile
+++ b/lambda/Makefile
@@ -29,7 +29,7 @@
 
 PROGRAMMER_TYPE = avrisp
 # extra arguments to avrdude: baud rate, chip type, -F flag, etc.
-PROGRAMMER_ARGS = -b 19200 -P /dev/ttyACM0
+PROGRAMMER_ARGS = -b 19200 -P /dev/ttyACM3
 
 ##########------------------------------------------------------##########
 ##########                   Makefile Magic!                    ##########