diff --git a/lib/cli.zsh b/lib/cli.zsh
index b1478a89f..30790bec7 100644
--- a/lib/cli.zsh
+++ b/lib/cli.zsh
@@ -351,7 +351,7 @@ function _omz::theme::use {
 
 function _omz::update {
     # Run update script
-    env ZSH="$ZSH" sh "$ZSH/tools/upgrade.sh"
+    env ZSH="$ZSH" zsh -f "$ZSH/tools/upgrade.sh"
     # Update last updated file
     zmodload zsh/datetime
     echo "LAST_EPOCH=$(( EPOCHSECONDS / 60 / 60 / 24 ))" >! "${ZSH_CACHE_DIR}/.zsh-update"
diff --git a/lib/functions.zsh b/lib/functions.zsh
index 15526cd5f..f6f34e851 100644
--- a/lib/functions.zsh
+++ b/lib/functions.zsh
@@ -14,7 +14,7 @@ function upgrade_oh_my_zsh() {
   fi
 
   # Run update script
-  env ZSH="$ZSH" sh "$ZSH/tools/upgrade.sh"
+  env ZSH="$ZSH" zsh -f "$ZSH/tools/upgrade.sh"
   # Update last updated file
   zmodload zsh/datetime
   echo "LAST_EPOCH=$(( EPOCHSECONDS / 60 / 60 / 24 ))" >! "${ZSH_CACHE_DIR}/.zsh-update"
diff --git a/tools/check_for_upgrade.sh b/tools/check_for_upgrade.sh
index cadd5fe49..17925af8b 100644
--- a/tools/check_for_upgrade.sh
+++ b/tools/check_for_upgrade.sh
@@ -1,6 +1,6 @@
 # Migrate .zsh-update file to $ZSH_CACHE_DIR
 if [[ -f ~/.zsh-update && ! -f "${ZSH_CACHE_DIR}/.zsh-update" ]]; then
-    mv ~/.zsh-update "${ZSH_CACHE_DIR}/.zsh-update"
+  mv ~/.zsh-update "${ZSH_CACHE_DIR}/.zsh-update"
 fi
 
 # Cancel update if:
@@ -10,79 +10,81 @@ fi
 if [[ "$DISABLE_AUTO_UPDATE" = true ]] \
    || [[ ! -w "$ZSH" || ! -O "$ZSH" ]] \
    || ! command -v git &>/dev/null; then
-    return
+  return
 fi
 
 
 function current_epoch() {
-    zmodload zsh/datetime
-    echo $(( EPOCHSECONDS / 60 / 60 / 24 ))
+  zmodload zsh/datetime
+  echo $(( EPOCHSECONDS / 60 / 60 / 24 ))
 }
 
 function update_last_updated_file() {
-    echo "LAST_EPOCH=$(current_epoch)" >! "${ZSH_CACHE_DIR}/.zsh-update"
+  echo "LAST_EPOCH=$(current_epoch)" >! "${ZSH_CACHE_DIR}/.zsh-update"
 }
 
 function update_ohmyzsh() {
-    ZSH="$ZSH" sh "$ZSH/tools/upgrade.sh"
-    update_last_updated_file
+  ZSH="$ZSH" zsh -f "$ZSH/tools/upgrade.sh"
+  update_last_updated_file
 }
 
 () {
-    emulate -L zsh
+  emulate -L zsh
 
-    local epoch_target mtime option LAST_EPOCH
+  local epoch_target mtime option LAST_EPOCH
 
-    # Remove lock directory if older than a day
-    zmodload zsh/datetime
-    zmodload -F zsh/stat b:zstat
-    if mtime=$(zstat +mtime "$ZSH/log/update.lock" 2>/dev/null); then
-        if (( (mtime + 3600 * 24) < EPOCHSECONDS )); then
-            command rm -rf "$ZSH/log/update.lock"
-        fi
+  # Remove lock directory if older than a day
+  zmodload zsh/datetime
+  zmodload -F zsh/stat b:zstat
+  if mtime=$(zstat +mtime "$ZSH/log/update.lock" 2>/dev/null); then
+    if (( (mtime + 3600 * 24) < EPOCHSECONDS )); then
+      command rm -rf "$ZSH/log/update.lock"
     fi
+  fi
 
-    # Check for lock directory
-    if ! command mkdir "$ZSH/log/update.lock" 2>/dev/null; then
-        return
-    fi
+  # Check for lock directory
+  if ! command mkdir "$ZSH/log/update.lock" 2>/dev/null; then
+    return
+  fi
 
-    # Remove lock directory on exit. `return 1` is important for when trapping a SIGINT:
-    #  The return status from the function is handled specially. If it is zero, the signal is
-    #  assumed to have been handled, and execution continues normally. Otherwise, the shell
-    #  will behave as interrupted except that the return status of the trap is retained.
-    trap "command rm -rf '$ZSH/log/update.lock'; return 1" EXIT INT QUIT
+  # Remove lock directory on exit. `return 1` is important for when trapping a SIGINT:
+  #  The return status from the function is handled specially. If it is zero, the signal is
+  #  assumed to have been handled, and execution continues normally. Otherwise, the shell
+  #  will behave as interrupted except that the return status of the trap is retained.
+  trap "
+  unset -f current_epoch update_last_updated_file update_ohmyzsh
+  command rm -rf '$ZSH/log/update.lock'
+  return 1
+  " EXIT INT QUIT
 
-    # Create or update .zsh-update file if missing or malformed
-    if ! source "${ZSH_CACHE_DIR}/.zsh-update" 2>/dev/null || [[ -z "$LAST_EPOCH" ]]; then
-        update_last_updated_file
-        return
-    fi
+  # Create or update .zsh-update file if missing or malformed
+  if ! source "${ZSH_CACHE_DIR}/.zsh-update" 2>/dev/null || [[ -z "$LAST_EPOCH" ]]; then
+    update_last_updated_file
+    return
+  fi
 
-    # Number of days before trying to update again
-    epoch_target=${UPDATE_ZSH_DAYS:-13}
-    # Test if enough time has passed until the next update
-    if (( ( $(current_epoch) - $LAST_EPOCH ) < $epoch_target )); then
-        return
-    fi
+  # Number of days before trying to update again
+  epoch_target=${UPDATE_ZSH_DAYS:-13}
+  # Test if enough time has passed until the next update
+  if (( ( $(current_epoch) - $LAST_EPOCH ) < $epoch_target )); then
+    return
+  fi
 
-    # Ask for confirmation before updating unless disabled
-    if [[ "$DISABLE_UPDATE_PROMPT" = true ]]; then
-        update_ohmyzsh
-    else
-        # input sink to swallow all characters typed before the prompt
-        # and add a newline if there wasn't one after characters typed
-        while read -t -k 1 option; do true; done
-        [[ "$option" != ($'\n'|"") ]] && echo
+  # Ask for confirmation before updating unless disabled
+  if [[ "$DISABLE_UPDATE_PROMPT" = true ]]; then
+    update_ohmyzsh
+  else
+    # input sink to swallow all characters typed before the prompt
+    # and add a newline if there wasn't one after characters typed
+    while read -t -k 1 option; do true; done
+    [[ "$option" != ($'\n'|"") ]] && echo
 
-        echo -n "[oh-my-zsh] Would you like to update? [Y/n] "
-        read -r -k 1 option
-        [[ "$option" != $'\n' ]] && echo
-        case "$option" in
-            [yY$'\n']) update_ohmyzsh ;;
-            [nN]) update_last_updated_file ;;
-        esac
-    fi
+    echo -n "[oh-my-zsh] Would you like to update? [Y/n] "
+    read -r -k 1 option
+    [[ "$option" != $'\n' ]] && echo
+    case "$option" in
+      [yY$'\n']) update_ohmyzsh ;;
+      [nN]) update_last_updated_file ;;
+    esac
+  fi
 }
-
-unset -f current_epoch update_last_updated_file update_ohmyzsh
diff --git a/tools/upgrade.sh b/tools/upgrade.sh
old mode 100644
new mode 100755
index e005519d6..634d5c03d
--- a/tools/upgrade.sh
+++ b/tools/upgrade.sh
@@ -1,13 +1,23 @@
-# Use colors, but only if connected to a terminal, and that terminal
-# supports them.
+#!/usr/bin/env zsh
+
+cd "$ZSH"
+
+# Use colors, but only if connected to a terminal
+# and that terminal supports them.
+
+local -a RAINBOW
+local RED GREEN YELLOW BLUE UNDER BOLD RESET
+
 if [ -t 1 ]; then
-  RB_RED=$(printf '\033[38;5;196m')
-  RB_ORANGE=$(printf '\033[38;5;202m')
-  RB_YELLOW=$(printf '\033[38;5;226m')
-  RB_GREEN=$(printf '\033[38;5;082m')
-  RB_BLUE=$(printf '\033[38;5;021m')
-  RB_INDIGO=$(printf '\033[38;5;093m')
-  RB_VIOLET=$(printf '\033[38;5;163m')
+  RAINBOW=(
+    "$(printf '\033[38;5;196m')"
+    "$(printf '\033[38;5;202m')"
+    "$(printf '\033[38;5;226m')"
+    "$(printf '\033[38;5;082m')"
+    "$(printf '\033[38;5;021m')"
+    "$(printf '\033[38;5;093m')"
+    "$(printf '\033[38;5;163m')"
+  )
 
   RED=$(printf '\033[31m')
   GREEN=$(printf '\033[32m')
@@ -16,25 +26,19 @@ if [ -t 1 ]; then
   BOLD=$(printf '\033[1m')
   UNDER=$(printf '\033[4m')
   RESET=$(printf '\033[m')
-else
-  RB_RED=""
-  RB_ORANGE=""
-  RB_YELLOW=""
-  RB_GREEN=""
-  RB_BLUE=""
-  RB_INDIGO=""
-  RB_VIOLET=""
-
-  RED=""
-  GREEN=""
-  YELLOW=""
-  BLUE=""
-  UNDER=""
-  BOLD=""
-  RESET=""
 fi
 
-cd "$ZSH"
+# Update upstream remote to ohmyzsh org
+git remote -v | while read remote url _; do
+  case "$url" in
+  https://github.com/robbyrussell/oh-my-zsh(|.git))
+    git remote set-url "$remote" "https://github.com/ohmyzsh/ohmyzsh.git"
+    break ;;
+  git@github.com:robbyrussell/oh-my-zsh(|.git))
+    git remote set-url "$remote" "git@github.com:ohmyzsh/ohmyzsh.git"
+    break ;;
+  esac
+done
 
 # Set git-config values known to fix git errors
 # Line endings (#4069)
@@ -45,30 +49,36 @@ git config fsck.zeroPaddedFilemode ignore
 git config fetch.fsck.zeroPaddedFilemode ignore
 git config receive.fsck.zeroPaddedFilemode ignore
 # autostash on rebase (#7172)
-resetAutoStash=$(git config --bool rebase.autoStash 2>&1)
+resetAutoStash=$(git config --bool rebase.autoStash 2>/dev/null)
 git config rebase.autoStash true
 
-# Update upstream remote to ohmyzsh org
-remote=$(git remote -v | awk '/https:\/\/github\.com\/robbyrussell\/oh-my-zsh\.git/{ print $1; exit }')
-if [ -n "$remote" ]; then
-  git remote set-url "$remote" "https://github.com/ohmyzsh/ohmyzsh.git"
-fi
+local ret=0
 
+# Update Oh My Zsh
 printf "${BLUE}%s${RESET}\n" "Updating Oh My Zsh"
-if git pull --rebase --stat origin master
-then
-  printf '%s         %s__      %s           %s        %s       %s     %s__   %s\n' $RB_RED $RB_ORANGE $RB_YELLOW $RB_GREEN $RB_BLUE $RB_INDIGO $RB_VIOLET $RB_RESET
-  printf '%s  ____  %s/ /_    %s ____ ___  %s__  __  %s ____  %s_____%s/ /_  %s\n' $RB_RED $RB_ORANGE $RB_YELLOW $RB_GREEN $RB_BLUE $RB_INDIGO $RB_VIOLET $RB_RESET
-  printf '%s / __ \%s/ __ \  %s / __ `__ \%s/ / / / %s /_  / %s/ ___/%s __ \ %s\n' $RB_RED $RB_ORANGE $RB_YELLOW $RB_GREEN $RB_BLUE $RB_INDIGO $RB_VIOLET $RB_RESET
-  printf '%s/ /_/ /%s / / / %s / / / / / /%s /_/ / %s   / /_%s(__  )%s / / / %s\n' $RB_RED $RB_ORANGE $RB_YELLOW $RB_GREEN $RB_BLUE $RB_INDIGO $RB_VIOLET $RB_RESET
-  printf '%s\____/%s_/ /_/ %s /_/ /_/ /_/%s\__, / %s   /___/%s____/%s_/ /_/  %s\n' $RB_RED $RB_ORANGE $RB_YELLOW $RB_GREEN $RB_BLUE $RB_INDIGO $RB_VIOLET $RB_RESET
-  printf '%s    %s        %s           %s /____/ %s       %s     %s          %s\n' $RB_RED $RB_ORANGE $RB_YELLOW $RB_GREEN $RB_BLUE $RB_INDIGO $RB_VIOLET $RB_RESET
-  printf "${BLUE}%s\n" "Hooray! Oh My Zsh has been updated and/or is at the current version."
-  printf "${BLUE}${BOLD}%s ${UNDER}%s${RESET}\n" "To keep up on the latest news and updates, follow us on Twitter:" "https://twitter.com/ohmyzsh"
+last_commit=$(git rev-parse HEAD)
+if git pull --rebase --stat origin master; then
+  # Check if it was really updated or not
+  if [[ "$(git rev-parse HEAD)" = "$last_commit" ]]; then
+    message="Oh My Zsh is already at the latest version."
+    ret=80 # non-zero exit code to indicate no changes pulled
+  else
+    message="Hooray! Oh My Zsh has been updated!"
+  fi
+
+  printf '%s         %s__      %s           %s        %s       %s     %s__   %s\n' $RAINBOW $RESET
+  printf '%s  ____  %s/ /_    %s ____ ___  %s__  __  %s ____  %s_____%s/ /_  %s\n' $RAINBOW $RESET
+  printf '%s / __ \%s/ __ \  %s / __ `__ \%s/ / / / %s /_  / %s/ ___/%s __ \ %s\n' $RAINBOW $RESET
+  printf '%s/ /_/ /%s / / / %s / / / / / /%s /_/ / %s   / /_%s(__  )%s / / / %s\n' $RAINBOW $RESET
+  printf '%s\____/%s_/ /_/ %s /_/ /_/ /_/%s\__, / %s   /___/%s____/%s_/ /_/  %s\n' $RAINBOW $RESET
+  printf '%s    %s        %s           %s /____/ %s       %s     %s          %s\n' $RAINBOW $RESET
+  printf '\n'
+  printf "${BLUE}%s${RESET}\n" "$message"
+  printf "${BLUE}${BOLD}%s ${UNDER}%s${RESET}\n" "To keep up with the latest news and updates, follow us on Twitter:" "https://twitter.com/ohmyzsh"
   printf "${BLUE}${BOLD}%s ${UNDER}%s${RESET}\n" "Want to get involved in the community? Join our Discord:" "https://discord.gg/ohmyzsh"
   printf "${BLUE}${BOLD}%s ${UNDER}%s${RESET}\n" "Get your Oh My Zsh swag at:" "https://shop.planetargon.com/collections/oh-my-zsh"
 else
-  status=$?
+  ret=$?
   printf "${RED}%s${RESET}\n" 'There was an error updating. Try again later?'
 fi
 
@@ -79,4 +89,4 @@ case "$resetAutoStash" in
 esac
 
 # Exit with `1` if the update failed
-exit $status
+exit $ret