diff --git a/build-go.sh b/build-go.sh
index cdd225c..ce060a3 100755
--- a/build-go.sh
+++ b/build-go.sh
@@ -1,10 +1,8 @@
 #!/bin/bash
 
 set -e
-if [ $(id -u) -ne 0 ]; then
-  echo "error: this script must be run as root">&2
-  exit 1
-fi
+errx() { echo "error: $1">&2; exit 1; }
+[[ $(id -u) -ne 0 ]] && errx "this script must be run as root"
 
 install_dir="/usr/local"
 go_dir="${install_dir}/go"
@@ -16,46 +14,48 @@ bootstrap="${install_dir}/bootstrap-${v14}"
 tgz14="${v14}.tar.gz"
 path_v14="${install_dir}/${tgz14}"
 
-new="go1.17"
-new_sum="d912e9db0fcbf69b7dacde058ee1675d0e3998905b8b2ab1080a5deb6df18f5d"
+v="${1-1.17.1}"
+case $v in
+  1.16.7) new_sum="07502f16366fbc697b1b09b842d29116e6d6607c9dc42b1d7c54b96f528c7952";;
+  1.17.1) new_sum="670ce36e100669f9be572a1603858ce4a64eb4b21a31fa5cdefb778609c40337";;
+  *) errx "no hash found for version ${v}";;
+esac
+
+new="go$v"
+new_dir="${install_dir}/go-${new}"
 tgznew="${new}.tar.gz"
 path_new="${install_dir}/${tgznew}"
 
-rm -rf ${go_dir}
+rm -f ${go_dir}
 
 if [[ ! -d "${bootstrap}" ]]; then
-  wget -q ${url}/${tgz14} -O ${path_v14}
-  if [[ "$(sha256sum ${path_v14}|cut -d" " -f1)" != "${v14_sum}" ]]; then
-    echo "error: wrong checksum: ${path_v14}">&2
-    exit 1
-  fi
+  curl -sSL "${url}/${tgz14}" >${path_v14}
+  [[ "$(sha256sum ${path_v14}|cut -d" " -f1)" != "${v14_sum}" ]] && errx "wrong checksum: ${path_v14}"
   tar xfz ${path_v14} -C ${install_dir}
   mv ${install_dir}/go-${v14} ${bootstrap}
 fi
 
-wget -q ${url}/${tgznew} -O ${path_new}
-if [[ "$(sha256sum ${path_new}|cut -d" " -f1)" != "${new_sum}" ]]; then
-  echo "error: wrong checksum: ${path_new}">&2
-  exit 1
+if [[ ! -d "${new_dir}" ]]; then
+  curl -sSL "${url}/${tgznew}" >${path_new}
+  [[ "$(sha256sum ${path_new}|cut -d" " -f1)" != "${new_sum}" ]] && errx "wrong checksum: ${path_new}"
+  tar xfz ${path_new} -C ${install_dir}
 fi
-tar xfz ${path_new} -C ${install_dir}
-mv ${install_dir}/go-${new} ${go_dir}
 
 export CGO_ENABLED=0
 
 if [[ ! -x "${bootstrap}/bin/go" ]]; then
   cd ${bootstrap}/src
-  #./make.bash &> /dev/null
   ./make.bash
 fi
 
-export GOROOT_BOOTSTRAP=${bootstrap}
+if [[ ! -x "${new_dir}/bin/go" ]]; then
+  export GOROOT_BOOTSTRAP=${bootstrap}
+  [[ "$(uname -m)" == "x86_64" ]] && export GOARCH=amd64 || export GOARCH=386
+  cd ${new_dir}/src
+  ./make.bash
+fi
 
-[[ "$(uname -m)" == "x86_64" ]] && export GOARCH=amd64 || export GOARCH=386
-
-cd ${go_dir}/src
-./make.bash
-#./make.bash &> /dev/null
+ln -s ${new_dir} ${go_dir}
 
 export GOROOT=${go_dir}
 export PATH=${PATH}:${GOROOT}/bin:~/go/bin
@@ -67,7 +67,7 @@ export CGO_ENABLED=${CGO_ENABLED}
 export GOPATH=~/go
 export GOROOT=${GOROOT}
 export GO111MODULE=on
-export PATH=\${PATH}:${GOROOT}:~/go/bin
+export PATH=\${PATH}:\${GOROOT}/bin:~/go/bin
 
 EOF