diff --git a/apps/web/public/install.sh b/apps/web/public/install.sh
index 3cc6c61..4a8fb38 100644
--- a/apps/web/public/install.sh
+++ b/apps/web/public/install.sh
@@ -1,12 +1,13 @@
-#!/usr/bin/env bash
+#!/bin/sh
 # c0upons CLI installer
 # Usage: curl -fsSL https://c0upons.com/install.sh | sh
-
-set -euo pipefail
+#
+# POSIX sh compatible — works under dash/sh as well as bash. Avoid bashisms
+# (pipefail, echo -e, [[ ]], &>) so `curl ... | sh` does not error.
+set -eu
 
 CLI_URL="https://c0upons.com/cli/c0upons"
 BIN_NAME="c0upons"
-BIN_DIR=""
 
 BOLD="\033[1m"
 GREEN="\033[32m"
@@ -14,15 +15,13 @@ ORANGE="\033[38;5;208m"
 DIM="\033[2m"
 RESET="\033[0m"
 
-echo ""
-echo -e "${BOLD}${ORANGE}c0upons${RESET} CLI installer"
-echo ""
+printf '\n'
+printf '%b\n' "${BOLD}${ORANGE}c0upons${RESET} CLI installer"
+printf '\n'
 
-# Detect install directory
+# Detect install directory: prefer /usr/local/bin when writable, else ~/.local/bin.
 if [ -w "/usr/local/bin" ]; then
   BIN_DIR="/usr/local/bin"
-elif [ -d "$HOME/.local/bin" ] && [[ ":$PATH:" == *":$HOME/.local/bin:"* ]]; then
-  BIN_DIR="$HOME/.local/bin"
 else
   BIN_DIR="$HOME/.local/bin"
   mkdir -p "$BIN_DIR"
@@ -30,29 +29,28 @@ fi
 
 DEST="$BIN_DIR/$BIN_NAME"
 
-echo -e "  Downloading from ${DIM}${CLI_URL}${RESET}"
+printf '%b\n' "  Downloading from ${DIM}${CLI_URL}${RESET}"
 curl -fsSL "$CLI_URL" -o /tmp/c0upons_install
 chmod +x /tmp/c0upons_install
 
-if [ "$BIN_DIR" = "/usr/local/bin" ]; then
-  if command -v sudo &>/dev/null; then
-    sudo mv /tmp/c0upons_install "$DEST"
-  else
-    mv /tmp/c0upons_install "$DEST"
-  fi
+if [ "$BIN_DIR" = "/usr/local/bin" ] && command -v sudo >/dev/null 2>&1; then
+  sudo mv /tmp/c0upons_install "$DEST"
 else
   mv /tmp/c0upons_install "$DEST"
 fi
 
-echo -e "  ${GREEN}✓${RESET} Installed to ${BOLD}${DEST}${RESET}"
-echo ""
-echo -e "  Run ${BOLD}c0upons help${RESET} to get started."
-echo ""
-
-if [[ ":$PATH:" != *":$BIN_DIR:"* ]]; then
-  echo -e "  ${DIM}Note: ${BIN_DIR} is not in your PATH.${RESET}"
-  echo -e "  ${DIM}Add it with:${RESET}"
-  echo ""
-  echo -e "    echo 'export PATH=\"${BIN_DIR}:\$PATH\"' >> ~/.bashrc && source ~/.bashrc"
-  echo ""
-fi
+printf '%b\n' "  ${GREEN}✓${RESET} Installed to ${BOLD}${DEST}${RESET}"
+printf '\n'
+printf '%b\n' "  Run ${BOLD}c0upons help${RESET} to get started."
+printf '\n'
+
+case ":$PATH:" in
+  *":$BIN_DIR:"*) ;;
+  *)
+    printf '%b\n' "  ${DIM}Note: ${BIN_DIR} is not in your PATH.${RESET}"
+    printf '%b\n' "  ${DIM}Add it with:${RESET}"
+    printf '\n'
+    printf '%b\n' "    echo 'export PATH=\"${BIN_DIR}:\$PATH\"' >> ~/.bashrc && source ~/.bashrc"
+    printf '\n'
+    ;;
+esac