diff --git a/install.sh b/install.sh
index 1b50204..bb3b4c0 100755
--- a/install.sh
+++ b/install.sh
@@ -96,8 +96,9 @@ if [ "${1:-}" = "-update" ]; then
         export GOPATH="${INSTALL_DIR}/.go"
         export GOCACHE="${INSTALL_DIR}/.go/build"
         mkdir -p "${GOMODCACHE}" "${GOCACHE}" 2>/dev/null || sudo_if mkdir -p "${GOMODCACHE}" "${GOCACHE}"
-        # Ensure the build cache is owned by the app user (was root from earlier builds).
-        sudo_if chown -R "${APP_USER:-${SUDO_USER:-$(whoami)}}" "${INSTALL_DIR}/.go" 2>/dev/null || true
+        # Ensure build cache and old binary are writable by the app user.
+        sudo_if chown -R "${APP_USER:-${SUDO_USER:-$(whoami)}}" "${INSTALL_DIR}/.go" "${INSTALL_DIR}/app" 2>/dev/null || true
+        rm -f app
         CGO_ENABLED=0 go build -buildvcs=false -ldflags="-s -w" -o app .
     else
         warn "Go not found — downloading pre-built binary..."
@@ -204,7 +205,8 @@ if command -v go &>/dev/null; then
     export GOCACHE="${INSTALL_DIR}/.go/build"
     mkdir -p "${GOMODCACHE}" "${GOCACHE}" 2>/dev/null || sudo_if mkdir -p "${GOMODCACHE}" "${GOCACHE}"
     # Ensure cache is owned by the app user.
-    sudo_if chown -R "$(whoami):$(whoami)" "${INSTALL_DIR}/.go" 2>/dev/null || true
+    sudo_if chown -R "$(whoami):$(whoami)" "${INSTALL_DIR}/.go" "${INSTALL_DIR}/app" 2>/dev/null || true
+    rm -f app
     CGO_ENABLED=0 go build -buildvcs=false -ldflags="-s -w" -o app .
 else
     info "Go not found — downloading pre-built binary..."