diff --git a/ROMFS/px4fmu_common/init.d/rcS b/ROMFS/px4fmu_common/init.d/rcS
index 51427c0cf657..da1e2212eb68 100644
--- a/ROMFS/px4fmu_common/init.d/rcS
+++ b/ROMFS/px4fmu_common/init.d/rcS
@@ -633,7 +633,7 @@ else
 	#
 	# Start the VTX services.
 	#
-	if ! param compare VTX_SER_CFG 0
+	if ! param compare -s VTX_SER_CFG 0
 	then
 		set RC_VTXTABLE ${R}etc/init.d/rc.vtxtable
 		if [ -f ${RC_VTXTABLE} ]