diff --git a/cmd/makemac/makemac.go b/cmd/makemac/makemac.go
index e97631ce7..1acfadf88 100644
--- a/cmd/makemac/makemac.go
+++ b/cmd/makemac/makemac.go
@@ -642,8 +642,7 @@ func autoAdjust() {
 		}
 	}()
 
-	req, _ := http.NewRequest("GET", "https://farmer.golang.org/status/reverse.json", nil)
-	req = req.WithContext(ctx)
+	req, _ := http.NewRequestWithContext(ctx, "GET", "https://farmer.golang.org/status/reverse.json", nil)
 	res, err := http.DefaultClient.Do(req)
 	if err != nil {
 		errors = append(errors, fmt.Sprintf("getting /status/reverse.json from coordinator: %v", err))
@@ -739,7 +738,7 @@ func (v Version) String() string {
 }
 
 // hostTypeToVersion determines the version of macOS from the host type.
-// Sample host types would be: host-darwin-10_12 and host-darwin-arm64-11_0.
+// Sample host types would be: host-darwin-10_15 and host-darwin-arm64-11_0.
 func hostTypeToVersion(hostType string) (*Version, error) {
 	v := &Version{}
 	var err error
@@ -747,32 +746,37 @@ func hostTypeToVersion(hostType string) (*Version, error) {
 		return nil, errors.New("unrecognized version")
 	}
 	htv := strings.TrimPrefix(hostType, "host-darwin-")
-	vs := strings.Split(htv, "-")
-	if len(vs) > 2 {
-		return nil, errors.New("unrecognized version")
-	}
 	var majorMinor string
-	if len(vs) == 2 {
+	switch vs := strings.Split(htv, "-"); len(vs) {
+	case 2:
 		if vs[0] != "amd64" && vs[0] != "arm64" {
 			return nil, errors.New("unrecognized version")
 		}
 		v.Arch = vs[0]
 		majorMinor = vs[1]
-	} else {
+	case 1:
 		v.Arch = "amd64"
 		majorMinor = vs[0]
-	}
-	mms := strings.Split(majorMinor, "_")
-	if len(mms) != 2 {
+	default:
 		return nil, errors.New("unrecognized version")
 	}
-	v.Major, err = strconv.Atoi(mms[0])
-	if err != nil {
-		return nil, err
-	}
-	v.Minor, err = strconv.Atoi(mms[1])
-	if err != nil {
-		return nil, err
+	switch mms := strings.Split(majorMinor, "_"); len(mms) {
+	case 1:
+		v.Major, err = strconv.Atoi(mms[0])
+		if err != nil {
+			return nil, err
+		}
+	case 2:
+		v.Major, err = strconv.Atoi(mms[0])
+		if err != nil {
+			return nil, err
+		}
+		v.Minor, err = strconv.Atoi(mms[1])
+		if err != nil {
+			return nil, err
+		}
+	default:
+		return nil, errors.New("unrecognized version")
 	}
 	return v, nil
 }
@@ -781,10 +785,10 @@ func hostTypeToVersion(hostType string) (*Version, error) {
 // or nil to not make anything. It gets the latest reverse buildlet
 // status from the coordinator.
 func wantedMacVersionNext(st *State, rstat *types.ReverseBuilderStatus) *Version {
-	// TODO: improve this logic now that the coordinator has a
-	// proper scheduler. Instead, don't create anything
-	// proactively until there's demand from it from the
-	// scheduler. (will need to add that to the coordinator's
+	// TODO(go.dev/issue/35698): improve this logic now that
+	// the coordinator has a proper scheduler. Instead, don't
+	// create anything proactively until there's demand from it
+	// from the scheduler. (will need to add that to the coordinator's
 	// status JSON) And maybe add a streaming endpoint to the
 	// coordinator so we don't need to poll every N seconds. Or
 	// just poll every few seconds, perhaps at a lighter endpoint
@@ -893,8 +897,7 @@ var (
 )
 
 func getLatestMacBuildlet(ctx context.Context) (bin []byte, err error) {
-	req, _ := http.NewRequest("HEAD", "https://storage.googleapis.com/go-builder-data/buildlet.darwin-amd64", nil)
-	req = req.WithContext(ctx)
+	req, _ := http.NewRequestWithContext(ctx, "HEAD", "https://storage.googleapis.com/go-builder-data/buildlet.darwin-amd64", nil)
 	res, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return nil, err
@@ -917,8 +920,7 @@ func getLatestMacBuildlet(ctx context.Context) (bin []byte, err error) {
 	buildletMu.Unlock()
 
 	log.Printf("fetching buildlet from GCS...")
-	req, _ = http.NewRequest("GET", "https://storage.googleapis.com/go-builder-data/buildlet.darwin-amd64", nil)
-	req = req.WithContext(ctx)
+	req, _ = http.NewRequestWithContext(ctx, "GET", "https://storage.googleapis.com/go-builder-data/buildlet.darwin-amd64", nil)
 	res, err = http.DefaultClient.Do(req)
 	if err != nil {
 		return nil, err
diff --git a/cmd/makemac/makemac_test.go b/cmd/makemac/makemac_test.go
index bae931822..28451f6e6 100644
--- a/cmd/makemac/makemac_test.go
+++ b/cmd/makemac/makemac_test.go
@@ -18,19 +18,19 @@ func TestHostTypeToVersion(t *testing.T) {
 	}{
 		{
 			desc:     "valid original darwin host type",
-			hostType: "host-darwin-10_11",
+			hostType: "host-darwin-10_14",
 			wantVersion: &Version{
 				Major: 10,
-				Minor: 11,
+				Minor: 14,
 				Arch:  "amd64",
 			},
 		},
 		{
 			desc:     "valid original darwin host type",
-			hostType: "host-darwin-10_12",
+			hostType: "host-darwin-10_15",
 			wantVersion: &Version{
 				Major: 10,
-				Minor: 12,
+				Minor: 15,
 				Arch:  "amd64",
 			},
 		},
@@ -52,6 +52,15 @@ func TestHostTypeToVersion(t *testing.T) {
 				Arch:  "amd64",
 			},
 		},
+		{
+			desc:     "valid newer darwin host AMD64",
+			hostType: "host-darwin-amd64-13",
+			wantVersion: &Version{
+				Major: 13,
+				Minor: 0,
+				Arch:  "amd64",
+			},
+		},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.desc, func(t *testing.T) {
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 334a9cdb3..63c8b1e2a 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -468,19 +468,9 @@ var Hosts = map[string]*HostConfig{
 		IsReverse:          true,
 		ExpectNum:          5,
 	},
-	"host-darwin-10_12": &HostConfig{
-		IsReverse: true,
-		ExpectNum: 2,
-		Notes:     "MacStadium OS X 10.12 VM under VMWare ESXi",
-		env: []string{
-			"GOROOT_BOOTSTRAP=/Users/gopher/go1.4",
-		},
-		SSHUsername:     "gopher",
-		HermeticReverse: true, // we destroy the VM when done & let cmd/makemac recreate
-	},
 	"host-darwin-10_14": &HostConfig{
 		IsReverse: true,
-		ExpectNum: 2,
+		ExpectNum: 3,
 		Notes:     "MacStadium macOS Mojave (10.14) VM under VMWare ESXi",
 		env: []string{
 			"GOROOT_BOOTSTRAP=/Users/gopher/goboot", // Go 1.12.1
@@ -500,7 +490,7 @@ var Hosts = map[string]*HostConfig{
 	},
 	"host-darwin-amd64-11_0": &HostConfig{
 		IsReverse: true,
-		ExpectNum: 4,
+		ExpectNum: 5,
 		Notes:     "MacStadium macOS Big Sur (11.0) VM under VMWare ESXi",
 		env: []string{
 			"GOROOT_BOOTSTRAP=/Users/gopher/goboot", // Go 1.13.4
@@ -2421,15 +2411,6 @@ func init() {
 		},
 		KnownIssues: []int{51019},
 	})
-	addBuilder(BuildConfig{
-		Name:           "darwin-amd64-10_12",
-		HostType:       "host-darwin-10_12",
-		distTestAdjust: macTestPolicy,
-		buildsRepo: func(repo, branch, goBranch string) bool {
-			// macOS 10.12 not supported after Go 1.16
-			return atMostGo1(goBranch, 16) && buildRepoByDefault(repo)
-		},
-	})
 	addBuilder(BuildConfig{
 		Name:           "darwin-amd64-10_14",
 		HostType:       "host-darwin-10_14",
diff --git a/dashboard/builders_test.go b/dashboard/builders_test.go
index 9509b96a8..36f5ac657 100644
--- a/dashboard/builders_test.go
+++ b/dashboard/builders_test.go
@@ -543,7 +543,6 @@ func TestBuilderConfig(t *testing.T) {
 		{b("darwin-amd64-10_14", "exp"), onlyPost},
 		{b("darwin-amd64-10_15", "exp"), onlyPost},
 		// ... but not on most others:
-		{b("darwin-amd64-10_12", "exp"), none},
 		{b("freebsd-386-11_4", "exp"), none},
 		{b("freebsd-386-12_3", "exp"), none},
 		{b("freebsd-amd64-11_4", "exp"), none},
@@ -560,7 +559,6 @@ func TestBuilderConfig(t *testing.T) {
 		{b("linux-amd64", "build"), both},
 		{b("linux-amd64-longtest", "build"), onlyPost},
 		{b("windows-amd64-2016", "build"), both},
-		{b("darwin-amd64-10_12", "build"), none},
 		{b("darwin-amd64-10_14", "build"), none},
 		{b("darwin-amd64-10_15", "build"), onlyPost},
 		{b("openbsd-amd64-68", "build"), none},
@@ -582,14 +580,10 @@ func TestBuilderConfig(t *testing.T) {
 		{b("android-amd64-emu", "build"), none},
 
 		// Only use latest macOS for subrepos, and only amd64:
-		{b("darwin-amd64-10_12@go1.16", "net"), onlyPost},
-		{b("darwin-amd64-10_12", "net"), none},
 		{b("darwin-amd64-10_14", "net"), onlyPost},
 
 		{b("darwin-amd64-10_15", "go"), onlyPost},
 		{b("darwin-amd64-10_14", "go"), onlyPost},
-		{b("darwin-amd64-10_12", "go"), none},
-		{b("darwin-amd64-10_12@go1.16", "go"), onlyPost},
 
 		// plan9 only lived at master. We didn't support any past releases.
 		// But it's off for now as it's always failing.
@@ -739,7 +733,6 @@ func TestShouldRunDistTest(t *testing.T) {
 		{"linux-amd64", "reboot", tryMode, true},
 		{"linux-amd64-race", "reboot", tryMode, false},
 
-		{"darwin-amd64-10_12", "test:foo", postSubmit, false},
 		{"darwin-amd64-10_14", "test:foo", postSubmit, false},
 		{"darwin-amd64-10_14", "reboot", postSubmit, false},
 		{"darwin-amd64-10_14", "api", postSubmit, false},
@@ -944,9 +937,10 @@ func TestMiscCompileLinuxGOARM5(t *testing.T) {
 	}
 }
 
-// TestExpectedMacstadiumVMCount ensures that only 20 instances of macOS virtual machines
-// are expected at MacStadium.
-// TODO: remove once the scheduler allocates VMs based on demand https://golang.org/issue/35698
+// TestExpectedMacstadiumVMCount ensures that the right number of
+// instances of macOS virtual machines are expected at MacStadium.
+//
+// TODO(go.dev/issue/35698): remove once the scheduler allocates VMs based on demand.
 func TestExpectedMacstadiumVMCount(t *testing.T) {
 	got := 0
 	for host, config := range Hosts {