diff --git a/ROMFS/px4fmu_common/init.d/rc.interface b/ROMFS/px4fmu_common/init.d/rc.interface
index 61abda3427..f3761200a1 100644
--- a/ROMFS/px4fmu_common/init.d/rc.interface
+++ b/ROMFS/px4fmu_common/init.d/rc.interface
@@ -121,7 +121,7 @@ then
 	then
 		if fmu mode_pwm
 		then
-			if [ -f $OUTPUT_AUX_DEV ]
+			if [ -e $OUTPUT_AUX_DEV ]
 			then
 				if mixer load $OUTPUT_AUX_DEV $MIXER_AUX_FILE
 				then