diff --git a/Library/Homebrew/completions/zsh.erb b/Library/Homebrew/completions/zsh.erb
index 2f401de7a1..87832e2483 100644
--- a/Library/Homebrew/completions/zsh.erb
+++ b/Library/Homebrew/completions/zsh.erb
@@ -44,7 +44,7 @@ __brew_completion_caching_policy() {
   (( $#tmp )) || return 0
 
   # otherwise, invalidate if latest tap index file is missing or newer than cache file
-  tmp=( ${HOMEBREW_REPOSITORY:-/usr/local/Homebrew}/Library/Taps/*/*/.git/index(om[1]N) )
+  tmp=( $(brew --repository)/Library/Taps/*/*/.git/index(om[1]N) )
   [[ -z $tmp || $tmp -nt $1 ]]
 }
 
diff --git a/completions/zsh/_brew b/completions/zsh/_brew
index 30e5658dd0..a5f526aa54 100644
--- a/completions/zsh/_brew
+++ b/completions/zsh/_brew
@@ -47,7 +47,7 @@ __brew_completion_caching_policy() {
   (( $#tmp )) || return 0
 
   # otherwise, invalidate if latest tap index file is missing or newer than cache file
-  tmp=( ${HOMEBREW_REPOSITORY:-/usr/local/Homebrew}/Library/Taps/*/*/.git/index(om[1]N) )
+  tmp=( $(brew --repository)/Library/Taps/*/*/.git/index(om[1]N) )
   [[ -z $tmp || $tmp -nt $1 ]]
 }