diff --git a/makefiles/config_px4fmu-v1_default.mk b/makefiles/config_px4fmu-v1_default.mk
index 6f39b56a13..cf631c2be5 100644
--- a/makefiles/config_px4fmu-v1_default.mk
+++ b/makefiles/config_px4fmu-v1_default.mk
@@ -24,14 +24,14 @@ MODULES		+= drivers/l3gd20
 MODULES		+= drivers/mpu6000
 MODULES		+= drivers/hmc5883
 MODULES		+= drivers/ms5611
-MODULES		+= drivers/mb12xx
+#MODULES		+= drivers/mb12xx
 MODULES		+= drivers/gps
 MODULES		+= drivers/hil
-MODULES		+= drivers/blinkm
+#MODULES		+= drivers/blinkm
 MODULES		+= drivers/rgbled
 MODULES		+= drivers/mkblctrl
 MODULES		+= drivers/airspeed
-MODULES		+= drivers/ets_airspeed
+#MODULES		+= drivers/ets_airspeed
 MODULES		+= drivers/meas_airspeed
 MODULES		+= drivers/frsky_telemetry
 MODULES		+= modules/sensors
diff --git a/src/lib/conversion/module.mk b/src/lib/conversion/module.mk
index f5f59a2dca..4593c48871 100644
--- a/src/lib/conversion/module.mk
+++ b/src/lib/conversion/module.mk
@@ -36,3 +36,5 @@
 #
 
 SRCS		 = rotation.cpp
+
+MAXOPTIMIZATION	 = -Os