Extra output when running commands from zsh in Guake

In zsh shell, I am having the following issue. After I press a command in command prompt, it is repeated in second line and also there's an ineligible character as well. I run zsh in Guake. Here's my .zshrc: a TERM="screen-256color" # install zsh antigen source /usr/share/zsh-antigen/antigen.zsh # Load the oh-my-zsh's library. antigen use oh-my-zsh # Bundles from the default repo (robbyrussell's oh-my-zsh). antigen bundle debian antigen bundle autojump antigen bundle cp antigen bundle colorize antigen bundle command-not-found antigen bundle git antigen bundle zsh-users/zsh-syntax-highlighting # Set Home for VirtualEnvWrapper export WORKON_HOME="$HOME/.config/virtualenv" antigen bundle virtualenvwrapper antigen bundle tmux antigen bundle littleq0903/gcloud-zsh-completion # Tell antigen that you're done. antigen apply # using system powerline source /usr/share/powerline/bindings/zsh/powerline.zsh export MANPAGER="/bin/sh -c \"col -b | vim -c 'set ft=man ts=8 nomod nolist noma' -\"" I started removing line by line to check, which one is causing the issue. I believe its the "antigen use oh-my-zsh". Another pain point: I tried a lot tmux.conf, but it just didn't work the only thing that worked is this and tmux=tmux -2.