diff --git a/go/build.sh b/go/build.sh
index d4f9f63..ee0a600 100755
--- a/go/build.sh
+++ b/go/build.sh
@@ -3,6 +3,11 @@ set -eu
 
 export MAKEFLAGS="-j${NPROC:-$(nproc)}"
 
-[ ! -d build/install-bootstrap ] && ./build_bootstrap.sh
-[ ! -d build/install-go19 ] && ./build_go19.sh
-[ ! -d build/install-go ] && ./build_go.sh
+version_go=1.22.0  # https://golang.org/dl/
+version_go21=1.21.7
+version_go19=1.19.13
+
+[ ! -d build/install-go1.4 ] && ./build_bootstrap.sh
+[ ! -d build/install-go1.19 ] && ./build_go.sh 1.4 1.19 "$version_go19"
+[ ! -d build/install-go1.21 ] && ./build_go.sh 1.19 1.21 "$version_go21"
+[ ! -d build/install-go ] && ./build_go.sh 1.21 '' "$version_go"
diff --git a/go/build_bootstrap.sh b/go/build_bootstrap.sh
index 89c08a3..30f97d5 100755
--- a/go/build_bootstrap.sh
+++ b/go/build_bootstrap.sh
@@ -5,7 +5,7 @@ version_bootstrap=20171003
 
 dir_download="$PWD/download"
 mkdir -p build; cd build
-dir_install="$PWD/install-bootstrap"
+dir_install="$PWD/install-go1.4"
 
 # Prepare source
 mkdir -p "go1.4-bootstrap-$version_bootstrap"
diff --git a/go/build_go.sh b/go/build_go.sh
index 62664b4..c0be05b 100755
--- a/go/build_go.sh
+++ b/go/build_go.sh
@@ -1,11 +1,13 @@
 #!/bin/sh
 set -eu
 
-version_go=1.21.0
+version_boot="$1"
+version_dest="$2"
+version_go="$3"
 
 dir_download="$PWD/download"
 mkdir -p build; cd build
-dir_install="$PWD/install-go"
+dir_install="$PWD/install-go$version_dest"
 
 # Prepare source
 mkdir -p "go$version_go"
@@ -13,7 +15,7 @@ tar xf "$dir_download/go$version_go.src.tar.gz" -C "go$version_go" --strip-compo
 cd "go$version_go"
 
 # Build and install
-(cd src; GOROOT_BOOTSTRAP="$PWD/../../install-go19" ./make.bash)
+(cd src; GOROOT_BOOTSTRAP="$PWD/../../install-go$version_boot" ./make.bash)
 
 find src -type f \( ! -name '*.go' \
     -a ! -name '*.c' \
diff --git a/go/build_go19.sh b/go/build_go19.sh
deleted file mode 100755
index 9bdf422..0000000
--- a/go/build_go19.sh
+++ /dev/null
@@ -1,32 +0,0 @@
-#!/bin/sh
-set -eu
-
-version_go19=1.19.12
-
-dir_download="$PWD/download"
-mkdir -p build; cd build
-dir_install="$PWD/install-go19"
-
-# Prepare source
-mkdir -p "go$version_go19"
-tar xf "$dir_download/go$version_go19.src.tar.gz" -C "go$version_go19" --strip-components 1
-cd "go$version_go19"
-
-# Build and install
-(cd src; GOROOT_BOOTSTRAP="$PWD/../../install-bootstrap" ./make.bash)
-
-find src -type f \( ! -name '*.go' \
-    -a ! -name '*.c' \
-    -a ! -name '*.h' \
-    -a ! -name '*.s' \
-    -a ! -name '*.S' \
-    -a ! -name 'p256_asm_table.bin' \
-\) -print -delete
-find src -type f -name '*_test.go' -print -delete
-find src -type d -name 'testdata' -print0 | xargs -0 rm -vrf
-find src -type d -empty -print -delete
-find pkg -type f -name '*.a' -print -delete
-find pkg -type d -empty -print -delete
-
-mkdir -p "$dir_install"
-cp -at "$dir_install" bin pkg src
diff --git a/go/download.sh b/go/download.sh
index 6aa858d..180aa78 100755
--- a/go/download.sh
+++ b/go/download.sh
@@ -1,14 +1,16 @@
 #!/bin/sh
 set -eu
 
-version_go=1.21.0  # https://golang.org/dl/
-version_go19=1.19.12
+version_go=1.22.0  # https://golang.org/dl/
+version_go21=1.21.7
+version_go19=1.19.13
 version_bootstrap=20171003  # https://golang.org/doc/install/source#go14
 
 mkdir -p download
 cd download
 
 wget -c "https://dl.google.com/go/go$version_go.src.tar.gz"
+wget -c "https://dl.google.com/go/go$version_go21.src.tar.gz"
 wget -c "https://dl.google.com/go/go$version_go19.src.tar.gz"
 wget -c "https://dl.google.com/go/go1.4-bootstrap-$version_bootstrap.tar.gz"
 
diff --git a/go/download.sha256 b/go/download.sha256
index cb8097c..62f9d1e 100644
--- a/go/download.sha256
+++ b/go/download.sha256
@@ -1,3 +1,4 @@
-ee5d50e0a7fd74ba1b137cb879609aaaef9880bf72b5d1742100e38ae72bb557  go1.19.12.src.tar.gz
-818d46ede85682dd551ad378ef37a4d247006f12ec59b5b755601d2ce114369a  go1.21.0.src.tar.gz
+ccf36b53fb0024a017353c3ddb22c1f00bc7a8073c6aac79042da24ee34434d3  go1.19.13.src.tar.gz
+00197ab20f33813832bff62fd93cca1c42a08cc689a32a6672ca49591959bff6  go1.21.7.src.tar.gz
+4d196c3d41a0d6c1dfc64d04e3cc1f608b0c436bd87b7060ce3e23234e1f4d5c  go1.22.0.src.tar.gz
 f4ff5b5eb3a3cae1c993723f3eab519c5bae18866b5e5f96fe1102f0cb5c3e52  go1.4-bootstrap-20171003.tar.gz
diff --git a/go/install_gentoo.txt b/go/install_gentoo.txt
new file mode 100644
index 0000000..717b721
--- /dev/null
+++ b/go/install_gentoo.txt
@@ -0,0 +1,11 @@
+# Update with GO_BOOTSTRAP_MIN version in dev-lang/go
+GO_BOOTSTRAP_MIN=1.20.14
+
+sudo rsync -rvP build/install-go/ /usr/lib/go-bootstrap
+sudo mkdir -p /var/db/pkg/dev-lang/go-bootstrap-$GO_BOOTSTRAP_MIN
+echo 0 | sudo tee /var/db/pkg/dev-lang/go-bootstrap-$GO_BOOTSTRAP_MIN/SLOT > /dev/null
+
+sudo emerge dev-lang/go
+
+sudo rm -rf /usr/lib/go-bootstrap
+sudo rm -rf /var/db/pkg/dev-lang/go-bootstrap-$GO_BOOTSTRAP_MIN