diff --git a/Library/Homebrew/cmd/update-bash.sh b/Library/Homebrew/cmd/update-bash.sh
index 83355202b6..b67e3d6e23 100755
--- a/Library/Homebrew/cmd/update-bash.sh
+++ b/Library/Homebrew/cmd/update-bash.sh
@@ -198,7 +198,7 @@ update-bash() {
       --simulate-from-current-branch) HOMEBREW_SIMULATE_FROM_CURRENT_BRANCH=1 ;;
       --*) ;;
       -*v*) HOMEBREW_VERBOSE=1 ;;
-      -*v*) HOMEBREW_DEBUG=1 ;;
+      -*d*) HOMEBREW_DEBUG=1 ;;
       -*) ;;
       *)
         echo "This command updates brew itself, and does not take formula names." >&2