diff --git a/Library/Homebrew/cmd/update-reset.sh b/Library/Homebrew/cmd/update-reset.sh
index 2274f0a7bd..60aa47bed6 100644
--- a/Library/Homebrew/cmd/update-reset.sh
+++ b/Library/Homebrew/cmd/update-reset.sh
@@ -26,7 +26,7 @@ homebrew-update-reset() {
     set -x
   fi
 
-  if [[ -z "${REPOS[]}" ]]
+  if [[ -z "${REPOS[*]}" ]]
   then
     REPOS+=("$HOMEBREW_REPOSITORY" "$HOMEBREW_LIBRARY"/Taps/*/*)
   fi