Segmentation Fault when using this Library to take a screenshot

[wenmana]

I was using the following code to take a screenshot:

using XCBased, FileIO, ColorTypes

x11_display = ENV["DISPLAY"]
conn = xcb_connect(x11_display)
setup = get_setup(conn)

screen = setup.screens[1]
width = screen.width_in_pixels
height = screen.height_in_pixels
root = screen.root

output_format = XCB_IMAGE_FORMAT_Z_PIXMAP
plane_mask = 2^32 - 1

rep = xcb_get_image(conn, output_format, root, 0, 0, width, height, plane_mask, checked = false)

reply = fetch(rep)

img_data = reply.data

img = Array{Any}(zeros(height, width))

for i in 1:length(img_data)/4
	# The next line is the one causing problems
	img[Int(ceil(i/width)),Int((4i%width)/4)+1] = RGBX(img_data[Int(4(i-1)+1)]/255, img_data[Int(4(i-1)+2)]/255, img_data[Int(4(i-1)+3)]/255)
end

save("./image.png", img)

xcb_disconnect(conn)

but got a segmentation fault:

signal (11): Segmentation fault
in expression starting at /home/wali/Documents/julia/xshot.jl:23
getindex at ./array.jl:805
unknown function (ip: 0x7faebf2cf9d6)
top-level scope at /home/wali/Documents/julia/xshot.jl:24
unknown function (ip: 0x7faf4635db5f)
unknown function (ip: 0x7faf4635e46c)
jl_toplevel_eval_in at /usr/bin/../lib/julia/libjulia-internal.so.1 (unknown line)
unknown function (ip: 0x7faf342cb837)
unknown function (ip: 0x7faf34302d33)
unknown function (ip: 0x7faf340f70f2)
unknown function (ip: 0x7faf3403bc3d)
unknown function (ip: 0x7faf3403cc6a)
unknown function (ip: 0x7faf3403cdb5)
unknown function (ip: 0x7faf46380ade)
repl_entrypoint at /usr/bin/../lib/julia/libjulia-internal.so.1 (unknown line)
main at julia (unknown line)
__libc_start_main at /usr/bin/../lib/libc.so.6 (unknown line)
_start at julia (unknown line)
Allocations: 10511937 (Pool: 10510873; Big: 1064); GC: 6
[1]    52961 segmentation fault (core dumped)  julia xshot.jl