[volume_pulse] grep warning

[bepnos]

Expected behavior

Running the pulse audio script gives the volume percentage in correct syntax to directly display this using i3blocks

Actual behavior

There is a grep warning right before the string gets printed so the block in the status bar is all messed up

i3blocks config relevant to blocklet(s)

[volume]
label=VOL
instance=Master
interval=1
signal=2
command=/usr/share/i3blocks/volume_pulse

Output of blocklet(s) when run from command line

grep: warning: stray \ before :
 38% [0:HiFi__hw_Generic__sink]
 38% [0]
#ffffff

Output of any relevant other commands that might help diagnostics

I am on Arch using i3blocks version 1.5.3 and using i3 version 4.22-4