#compdef killall

if [[ "$OSTYPE" = linux* ]]; then
  _alternative \
      'signals:: _signals -p' \
      'processes:process:{ compadd "$expl[@]" ${${${(f)"$(_call processes-names ps ${${EUID/(#s)0(#e)/xa}//[0-9]#/} ho cmd 2> /dev/null)"//[][]/}:#(ps|COMMAND)}%%\ *} }'
else
  _signals -p
fi