diff --git a/ROMFS/px4fmu_common/init.d/rcS b/ROMFS/px4fmu_common/init.d/rcS
index 23312e4f5e..ed19f648a8 100644
--- a/ROMFS/px4fmu_common/init.d/rcS
+++ b/ROMFS/px4fmu_common/init.d/rcS
@@ -511,7 +511,7 @@ then
 		fi
 	fi
 
-	if [ $MAVLINK_F == "none" ]
+	if [ "x$MAVLINK_F" == xnone ]
 	then
 	else
 		mavlink start $MAVLINK_F