diff --git a/.profile b/.profile
index 006a8a8..b767732 100644
--- a/.profile
+++ b/.profile
@@ -22,21 +22,25 @@ export _JAVA_OPTIONS="-Dawt.useSystemAAFontSettings=on -Dswing.defaultlaf=com.su
 export QT_QPA_PLATFORMTHEME=gtk2
 export GOPATH="$HOME/.cache/go"
 
+exists() { which $@ 0<&- 1>/dev/null 2>/dev/null; }
+
 export LESS="-RNI"
 export PAGER="less $LESS"
-export LESS_TERMCAP_mb=$(tput bold; tput setaf 2) # green
-export LESS_TERMCAP_md=$(tput bold; tput setaf 6) # cyan
-export LESS_TERMCAP_me=$(tput sgr0)
-export LESS_TERMCAP_so=$(tput bold; tput setaf 4) # blue
-export LESS_TERMCAP_se=$(tput rmso; tput sgr0)
-export LESS_TERMCAP_us=$(tput smul; tput bold; tput setaf 7) # white
-export LESS_TERMCAP_ue=$(tput rmul; tput sgr0)
-export LESS_TERMCAP_mr=$(tput rev)
-export LESS_TERMCAP_mh=$(tput dim)
-export LESS_TERMCAP_ZN=$(tput ssubm)
-export LESS_TERMCAP_ZV=$(tput rsubm)
-export LESS_TERMCAP_ZO=$(tput ssupm)
-export LESS_TERMCAP_ZW=$(tput rsupm)
+if exists tput; then
+    export LESS_TERMCAP_mb=$(tput bold; tput setaf 2) # green
+    export LESS_TERMCAP_md=$(tput bold; tput setaf 6) # cyan
+    export LESS_TERMCAP_me=$(tput sgr0)
+    export LESS_TERMCAP_so=$(tput bold; tput setaf 4) # blue
+    export LESS_TERMCAP_se=$(tput rmso; tput sgr0)
+    export LESS_TERMCAP_us=$(tput smul; tput bold; tput setaf 7) # white
+    export LESS_TERMCAP_ue=$(tput rmul; tput sgr0)
+    export LESS_TERMCAP_mr=$(tput rev)
+    export LESS_TERMCAP_mh=$(tput dim)
+    export LESS_TERMCAP_ZN=$(tput ssubm)
+    export LESS_TERMCAP_ZV=$(tput rsubm)
+    export LESS_TERMCAP_ZO=$(tput ssupm)
+    export LESS_TERMCAP_ZW=$(tput rsupm)
+fi
 
 # Source secret keys and values into environment
 if [ -f "$CONFIG_DIR/secrets" ]; then
@@ -46,17 +50,17 @@ if [ -f "$CONFIG_DIR/secrets" ]; then
 fi
 
 # Merge system clipboards
-if [ -n "$DISPLAY" ] && which autocutsel >/dev/null 2>&1; then
+if [ -n "$DISPLAY" ] && exists autocutsel; then
     autocutsel -fork
     autocutsel -selection PRIMARY -fork
 fi
 
-if [ -z "$DBUS_SESSION_BUS_ADDRESS" ] && which dbus-launch >/dev/null 2>&1; then
+if [ -z "$DBUS_SESSION_BUS_ADDRESS" ] && exists dbus-launch; then
     eval $(dbus-launch --sh-syntax --exit-with-session)
     dbus-update-activation-environment --systemd DISPLAY
 fi
 
 # Start the gnome-keyring if it's installed
-if which gnome-keyring-daemon >/dev/null 2>&1; then
+if exists gnome-keyring-daemon; then
     export $(/usr/bin/gnome-keyring-daemon --start --components=pkcs11,secrets,ssh,gnupg)
 fi
diff --git a/.zshrc b/.zshrc
index 8cad46c..4849327 100644
--- a/.zshrc
+++ b/.zshrc
@@ -13,8 +13,10 @@ HISTFILE="$ZSH_DIR/histfile"
 HISTSIZE=999999
 SAVEHIST=999999
 
+exists() { which $@ 0<&- 1>/dev/null 2>/dev/null; }
+
 # Only set tty if running interactively
-if tty -s; then
+if exists tty && tty -s; then
     # Resolve at shell runtime
     export GPG_TTY="$(tty)"
 fi
@@ -23,13 +25,12 @@ fi
 setopt sharehistory histignorealldups histignorespace histreduceblanks
 setopt pathdirs autocd autopushd extendedglob alwaystoend dvorak
 
-
 # Completion initialisation
 autoload -U compinit ; compinit
 autoload -U bashcompinit ; bashcompinit
 
 # gopass completion
-if gopass --help &>/dev/null; then
+if exists gopass; then
     source <(gopass completion bash)
 fi
 
@@ -44,7 +45,7 @@ zstyle ':compinstall'  filename "$HOME/.zshrc"
 # Load antigen & plugins
 antigen_src="$ZSH_DIR/antigen.zsh"
 if [ ! -f "$antigen_src" ]; then
-    if which curl &>/dev/null; then
+    if exists curl; then
         getcmd='curl -L'
     else
         getcmd='wget -qO-'
diff --git a/aliases b/aliases
index 4685f6d..945ad46 100644
--- a/aliases
+++ b/aliases
@@ -61,7 +61,7 @@ alias ssh="ssh -tt"
 alias grip='grip --user=frebib --pass=$GRIP_API_KEY'
 alias acme.sh='acme.sh --home $XDG_CONFIG_HOME/acme.sh --config-home $XDG_CONFIG_HOME/acme.sh --log $XDG_CONFIG_HOME/acme.sh/acme.sh.log'
 alias acmesh='acme.sh --home $XDG_CONFIG_HOME/acme.sh --config-home $XDG_CONFIG_HOME/acme.sh --log $XDG_CONFIG_HOME/acme.sh/acme.sh.log'
-which gopass 1>/dev/null 2>/dev/null && alias pass='gopass'
+exists gopass && alias pass='gopass'
 alias abuild='docker run -ti --rm \
     -e USER \
     -e PWD \