diff --git a/completions/zsh/_brew_cask b/completions/zsh/_brew_cask
index 3293319c80..314fe0c680 100644
--- a/completions/zsh/_brew_cask
+++ b/completions/zsh/_brew_cask
@@ -49,6 +49,7 @@ __brew_cask_commands() {
     'search:searches all known Casks'
     'style:checks Cask style using RuboCop'
     'uninstall:uninstalls the given Cask'
+    'upgrade:upgrade installed Casks with newer versions'
     'zap:zaps all files associated with the given Cask'
   )
   _describe -t commands "brew cask command" commands
@@ -159,6 +160,13 @@ _brew_cask_uninstall() {
     '*::token:__brew_installed_casks'
 }
 
+_brew_cask_upgrade() {
+  _arguments : \
+    '--force:upgrade even if Cask is not present, and --force the install' \
+    '--greedy:also upgrade Casks with auto_updates or version \:latest' \
+    '*::token:__brew_installed_casks'
+}
+
 _brew_cask_zap() {
   __brew_all_casks
 }