diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index eb42634..3db4aae 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,9 +1,10 @@
 name: ci
 on:
   push:
+    branches: [ main ]
   workflow_dispatch:
   pull_request:
-    types: [opened, synchronize, reopened]
+    types: [ opened, synchronize, reopened ]
 jobs:
   cibuild:
     name: cibuild
@@ -32,6 +33,8 @@ jobs:
       run:
         shell: bash
     steps:
+      - run: env
+      - run: go env
       - uses: actions/checkout@v3.3.0
       - run: script/bootstrap
       - run: script/test
diff --git a/.github/workflows/integration.yml b/.github/workflows/integration.yml
index d252165..23b324c 100644
--- a/.github/workflows/integration.yml
+++ b/.github/workflows/integration.yml
@@ -1,9 +1,10 @@
 name: integration
 on:
   push:
+    branches: [ main ]
   workflow_dispatch:
   pull_request:
-    types: [opened, synchronize, reopened]
+    types: [ opened, synchronize, reopened ]
 jobs:
   install_go_tip:
     name: install tip
diff --git a/src/install-go b/src/install-go
index 0d35fd3..7e6db22 100755
--- a/src/install-go
+++ b/src/install-go
@@ -2,6 +2,7 @@
 
 # required global vars:
 # RUNNER_TOOL_CACHE         # provided by action
+# GITHUB_OUTPUT             # provided by action
 #
 # optional vars:
 # INSTALL_GO_FORCE                                     # set to non-empty to force the install
@@ -37,7 +38,9 @@ GITHUB_PATH="${GITHUB_PATH:-/dev/null}"
 add_to_github_path "$target_dir/bin"
 PATH="$(add_to_system_path "$target_dir/bin")"
 
-gopath=$(go env GOPATH)
+go_exec="$target_dir/bin/$(exe_name go)"
+
+gopath=$("$go_exec" env GOPATH)
 mkdir -p "$gopath/bin"
 
 add_to_github_path "$gopath/bin"
@@ -46,7 +49,7 @@ PATH="$(add_to_system_path "$gopath/bin")"
 unset GOROOT
 
 if [ -n "$INSTALL_GO_TIP" ]; then
-  GO111MODULE=off go get golang.org/dl/gotip
+  GO111MODULE=off "$go_exec" get golang.org/dl/gotip
   "$gopath/bin/$(exe_name gotip)" download
   rm -rf "$tip_target_dir"
   mkdir -p "$(dirname "$tip_target_dir")"
@@ -54,6 +57,7 @@ if [ -n "$INSTALL_GO_TIP" ]; then
 
   add_to_github_path "$tip_target_dir/bin"
   PATH="$(add_to_system_path "$tip_target_dir/bin")"
+  go_exec="$tip_target_dir/bin/$(exe_name go)"
 fi
 
 govars='GOCACHE
@@ -62,8 +66,8 @@ GOPATH
 GOROOT
 GOTOOLDIR'
 
-echo "GOROOT=$(go env GOROOT)" >> "$GITHUB_ENV"
+echo "GOROOT=$("$go_exec" env GOROOT)" >> "$GITHUB_ENV"
 
 for var in $govars; do
-  echo "$var=$(go env "$var")" >> "$GITHUB_OUTPUT"
+  echo "$var=$("$go_exec" env "$var")" >> "$GITHUB_OUTPUT"
 done
diff --git a/src/lib b/src/lib
index d0833ee..f9435d0 100755
--- a/src/lib
+++ b/src/lib
@@ -70,7 +70,7 @@ download_go_url() {
 }
 
 install_go() {
-  local go_version="$1"
+  local go_version="${1#go}"
   local target_dir="$2"
   debug_out "installing go $go_version to $target_dir"
   rm -rf "$target_dir"
@@ -160,8 +160,6 @@ select_local_version() {
 select_remote_version() {
   local constraint="$1"
   local versions="$2"
-  # shellcheck disable=SC2001
-  versions="$(echo "$versions" | sed 's/^go//g')"
 
   if got="$(select_go_version "$constraint" "$versions")"; then
     echo "$got" && return
@@ -172,7 +170,7 @@ select_remote_version() {
     return
   fi
 
-  echo "$versions" | ./src/"semver-select" --go -c "$constraint" -n 1 -i -
+  echo "$versions" | ./src/"semver-select" --orig --go -c "$constraint" -n 1 -i -
 }
 
 # uses semver-select to convert a go version to semver
diff --git a/src/lib.pl b/src/lib.pl
index c7b7800..2fc1c6d 100644
--- a/src/lib.pl
+++ b/src/lib.pl
@@ -2,24 +2,17 @@
 use strict;
 use warnings;
 
-my $exp = qr/^(x|\d+)(\.(x|\d+)(\.(x|\d+))?)?(\w+)?$/;
+my $exp = qr/^(?:go)?(?<major>x|\d+)(?:\.(?<minor>x|\d+)(?:\.(?<patch>x|\d+))?)?(?<pre_release>\w+)?$/;
 
 sub parse_go_version {
     my $ver = shift;
     return unless $ver =~ m/$exp/;
-    my $major       = $1;
-    my $minor       = $3;
-    my $patch       = $5;
-    my $pre_release = $6;
-    $major       = 0  unless $major;
-    $minor       = 0  unless $minor;
-    $patch       = 0  unless $patch;
-    $pre_release = "" unless $pre_release;
     my $result = {
-        major       => $major,
-        minor       => $minor,
-        patch       => $patch,
-        pre_release => $pre_release
+        original    => $&,
+        major       => $+{major} || 0,
+        minor       => $+{minor} || 0,
+        patch       => $+{patch} || 0,
+        pre_release => $+{pre_release} || ""
     };
     return unless is_valid_go_version_pattern($result);
     return $result;
@@ -45,7 +38,7 @@ sub go_version_greater {
     # false if a is a pre-release and b isn't
     return 0 if $$a{"pre_release"} ne "" && $$b{"pre_release"} eq "";
 
-    # true if a's preview is asciibetical ahead of b's
+    # true if a's pre-release is asciibetical ahead of b's
     return 1 if $$a{"pre_release"} gt $$b{"pre_release"};
     return 0;
 }
@@ -67,34 +60,6 @@ ()
     return 1;
 }
 
-sub go_version_string {
-    my $v       = shift;
-    my $major_v = $$v{"major"};
-    my $minor_v = $$v{"minor"};
-    my $patch_v = $$v{"patch"};
-
-    # For 1.21 and above with no pre-release, always return major.minor.patch
-    if ( $major_v > 1 || ( $major_v == 1 && $minor_v >= 21 ) ) {
-        if ( $$v{"pre_release"} eq "" ) {
-            return "$major_v.$minor_v.$patch_v";
-        }
-    }
-
-    $patch_v = "" if $patch_v == 0;
-    $minor_v = "" if $minor_v == 0 && $patch_v eq "";
-    my $st = "$$v{'major'}";
-    if ( $minor_v ne "" ) {
-        $st = "$st.$minor_v";
-    }
-    if ( $patch_v ne "" ) {
-        $st = "$st.$patch_v";
-    }
-    if ( $$v{"pre_release"} ) {
-        $st = "$st$$v{'pre_release'}";
-    }
-    return $st;
-}
-
 sub go_version_pattern_match {
     my $pattern = shift;
     my $ver     = shift;
@@ -106,10 +71,4 @@ sub go_version_pattern_match {
     return 1;
 }
 
-sub exit_err() {
-    my $msg = shift;
-    print "$msg\n";
-    exit 1;
-}
-
 1;
diff --git a/src/lib_test.pl b/src/lib_test.pl
index cf3625e..8fe4bfb 100755
--- a/src/lib_test.pl
+++ b/src/lib_test.pl
@@ -36,19 +36,5 @@ sub parse_and_match {
 ok( parse_and_match( "1.2.x", "1.2.3" ) == 1 );
 ok( parse_and_match( "1.2.x", "1.2.3beta1" ) == 0 );
 
-sub test_go_version_string {
-    my $in = shift;
-    my $p  = parse_go_version($in);
-    ok( go_version_string($p) eq $in, "test_go_version_string $in" );
-}
-
-test_go_version_string "1.2.3";
-test_go_version_string "1";
-test_go_version_string "0";
-test_go_version_string "1.0.1";
-test_go_version_string "1.1";
-test_go_version_string "1.1beta1";
-test_go_version_string "1beta1";
-
 done_testing();
 
diff --git a/src/lib_test.sh b/src/lib_test.sh
index 7ef23dd..da03300 100755
--- a/src/lib_test.sh
+++ b/src/lib_test.sh
@@ -93,47 +93,47 @@ test_select_go_version() {
   do_test_select_go_version "" "1.2.3"
   do_test_select_go_version "1.21.0" "1.21.x" "1.21.0"
   do_test_select_go_version "1.21.0" "1.21" "1.21.0"
-  do_test_select_go_version "1.20" "1.20.x" "1.20.0"
+  do_test_select_go_version "go1.20" "1.20.x" "go1.20"
 }
 
 test_select_remote_version() {
-  versions='1.15.7
-1.15.6
-1.14.3
-1.15.6
-1.15.5
-1.15.4
-1.15.3
-1.15.2
-1.15.1
-1.15
-1.14.3
-1.14.2
-1.14.1
-1.14
-1.13.3
-1.13.2
-1.13.1
-1.13
-1.3.3
-1.3.2
-1.3.1
-1.3
-1.2.2
-1
-1.16beta1
-1.16rc1'
-
-  tests='*;1.15.7
+  versions='go1.15.7
+go1.15.6
+go1.14.3
+go1.15.6
+go1.15.5
+go1.15.4
+go1.15.3
+go1.15.2
+go1.15.1
+go1.15
+go1.14.3
+go1.14.2
+go1.14.1
+go1.14
+go1.13.3
+go1.13.2
+go1.13.1
+go1.13
+go1.3.3
+go1.3.2
+go1.3.1
+go1.3
+go1.2.2
+go1
+go1.16beta1
+go1.16rc1'
+
+  tests='*;go1.15.7
 1.17.x;
 1.16.x;
-1.15;1.15
-1.15.x;1.15.7
-^1;1.15.7
+1.15;go1.15
+1.15.x;go1.15.7
+^1;go1.15.7
 ^1.15.999;
-1.13.x;1.13.3
-1.16beta1;1.16beta1
-x;1.15.7'
+1.13.x;go1.13.3
+1.16beta1;go1.16beta1
+x;go1.15.7'
 
   for td in $tests; do
     input="$(echo "$td" | cut -d ';' -f1)"
diff --git a/src/run b/src/run
index ec3cd01..391a60e 100755
--- a/src/run
+++ b/src/run
@@ -2,11 +2,19 @@
 
 # required global vars:
 # RUNNER_TOOL_CACHE         # provided by action
+# RUNNER_WORKSPACE          # provided by action
+# GITHUB_ACTION_PATH        # provided by action
+# GITHUB_OUTPUT             # provided by action
 #
 # optional vars:
 # GO_VERSION= version constraint
 # GO_VERSION_FILE= path to go.mod or go.work
-# INSTALL_GO_FORCE                                     # set to non-empty to force the install
+# INSTALL_GO_FORCE   # set to non-empty to force the install
+# IGNORE_LOCAL_GO    # set to non-empty to ignore local go installations
+#
+# for testing:
+# VERSIONS_URL       # override the url used to get the list of known versions
+# SKIP_MATCHER       # don't issue the add-matcher command because it breaks when running tests on windows
 
 set -e
 [ -n "$DEBUG" ] && set -x
@@ -15,6 +23,8 @@ CDPATH="" cd -- "$(dirname -- "$0")/.."
 
 . src/lib
 
+VERSIONS_URL="${VERSIONS_URL:-https://raw.githubusercontent.com/WillAbides/goreleases/main/versions.txt}"
+
 debug_out starting run
 
 export INSTALL_GO_TIP
@@ -49,25 +59,25 @@ mkdir -p "$go_tool_cache"
 
 if [ -z "$IGNORE_LOCAL_GO" ]; then
   lv="$(select_local_version "$constraint" "$install_parent")"
-  target_dir="$install_parent/$lv/x64"
+  target_dir="$install_parent/${lv#go}/x64"
 fi
 
 if [ -z "$IGNORE_LOCAL_GO" ] && [ -z "$lv" ]; then
   lv="$(select_local_version "$constraint" "$go_tool_cache")"
-  target_dir="$go_tool_cache/$lv/x64"
+  target_dir="$go_tool_cache/${lv#go}/x64"
 fi
 
 if [ -z "$lv" ]; then
   if is_precise_version "$constraint"; then
     lv="$constraint"
-    target_dir="$install_parent/$lv/x64"
+    target_dir="$install_parent/${lv#go}/x64"
   fi
 fi
 
 if [ -z "$lv" ]; then
-  known_versions="$(curl --retry 4 -s --fail 'https://raw.githubusercontent.com/WillAbides/goreleases/main/versions.txt')"
+  known_versions="$(curl --retry 4 -s --fail "$VERSIONS_URL")"
   lv="$(select_remote_version "$constraint" "$known_versions")"
-  target_dir="$install_parent/$lv/x64"
+  target_dir="$install_parent/${lv#go}/x64"
 fi
 
 if [ -z "$lv" ]; then
@@ -75,6 +85,6 @@ if [ -z "$lv" ]; then
   exit 1
 fi
 
-echo "::add-matcher::$GITHUB_ACTION_PATH/matchers.json"
+[ -n "$SKIP_MATCHER" ] || echo "::add-matcher::$GITHUB_ACTION_PATH/matchers.json"
 
 src/install-go "$lv" "$target_dir" "$install_parent/tip/x64"
diff --git a/src/run_test_long.sh b/src/run_test_long.sh
new file mode 100755
index 0000000..5c7a0c3
--- /dev/null
+++ b/src/run_test_long.sh
@@ -0,0 +1,74 @@
+#!/bin/bash
+
+set -e
+
+CDPATH="" cd -- "$(dirname -- "$0")/.."
+
+setUp() {
+  . src/lib
+}
+
+# Nothing special about this one. It just happens to be HEAD of main when writing this.
+# Most recent version is go1.21rc4
+STABLE_VERSIONS_URL="https://raw.githubusercontent.com/WillAbides/goreleases/077db58ac86a8a2fb63c90817090e132eded0f3d/versions.txt"
+
+do_test_run() {
+  tmp_dir="$SHUNIT_TMPDIR"/test_run
+  rm -rf -- "$tmp_dir"
+  mkdir -p -- "$tmp_dir"
+  export RUNNER_TEMP="$tmp_dir/runner_temp"
+  export RUNNER_TOOL_CACHE="$tmp_dir/runner_tool_cache"
+  export RUNNER_WORKSPACE="$tmp_dir/runner_workspace"
+  export GITHUB_OUTPUT="$tmp_dir/github_output"
+  export GITHUB_ACTION_PATH="$PWD"
+  export VERSIONS_URL="$STABLE_VERSIONS_URL"
+  export SKIP_MATCHER=1
+  export IGNORE_LOCAL_GO=1
+  export GOROOT=""
+  ./src/run
+  WANT_GOROOT="$RUNNER_WORKSPACE/setup-go-faster/go/$WANT_VERSION/x64"
+  if [ "$(goos)" = "windows" ]; then
+    # Windows is trickier because of how it translates paths.
+    # Just check that is has the right suffix.
+    WANT_GOROOT="setup-go-faster\\go\\$WANT_VERSION\\x64"
+  fi
+  assertContains "$(grep '^GOROOT=' "$GITHUB_OUTPUT")" "$WANT_GOROOT"
+}
+
+test_run_1_15_x() {
+  GO_VERSION="1.15.x" \
+    WANT_VERSION="1.15.15" \
+    do_test_run
+}
+
+test_run_star() {
+  GO_VERSION="*" \
+    WANT_VERSION="1.20.7" \
+    do_test_run
+}
+
+test_run_1_16rc1() {
+  GO_VERSION="1.16rc1" \
+    WANT_VERSION="1.16rc1" \
+    do_test_run
+}
+
+test_run_1_21rc4() {
+  GO_VERSION="1.21rc4" \
+    WANT_VERSION="1.21rc4" \
+    do_test_run
+}
+
+test_go_mod() {
+  GO_VERSION_FILE="$SHUNIT_TMPDIR"/test_go_mod/go.mod
+  mkdir -p -- "$(dirname -- "$GO_VERSION_FILE")"
+  echo "
+module foo
+go 1.20.7 // the go version
+" > "$GO_VERSION_FILE"
+  GO_VERSION_FILE="$GO_VERSION_FILE" \
+    WANT_VERSION="1.20.7" \
+    do_test_run
+}
+
+. ./external/shunit2
diff --git a/src/select_go_version.pl b/src/select_go_version.pl
index 246fe1d..3c2d449 100755
--- a/src/select_go_version.pl
+++ b/src/select_go_version.pl
@@ -10,9 +10,16 @@
 my $usage = "usage: echo <versions...> | select_go_version.pl pattern";
 
 my $pat_arg = shift;
-exit_err($usage) unless $pat_arg;
+unless ($pat_arg) {
+    print "$usage\n";
+    exit 1;
+}
+
 my $pat = parse_go_version($pat_arg);
-exit_err("invalid pattern: $pat_arg") unless $pat;
+unless ($pat) {
+    print "invalid pattern: $pat_arg\n";
+    exit 1;
+}
 
 my $max;
 
@@ -26,4 +33,5 @@
 }
 
 exit 1 unless $max;
-print go_version_string($max) . "\n";
+
+print $$max{"original"} . "\n";
diff --git a/src/semver-select b/src/semver-select
index 73fdf76..70de7b0 100755
--- a/src/semver-select
+++ b/src/semver-select
@@ -5,24 +5,9 @@ set -e
 
 CDPATH="" cd -- "$(dirname -- "$0")/.."
 
-goos() {
-  case "$RUNNER_OS" in
-    macOS)
-      echo "darwin"
-      ;;
-    Linux)
-      echo "linux"
-      ;;
-    Windows)
-      echo "windows"
-      ;;
-    *)
-      uname -s | tr '[:upper:]' '[:lower:]'
-      ;;
-  esac
-}
+. src/lib
 
-target_version="0.3.0"
+target_version="0.4.0"
 bin_path="./bin/semver-select"
 [ "$(goos)" = "windows" ] && bin_path+=".exe"