diff --git a/.github/workflows/go.yaml b/.github/workflows/go.yaml
index 7dbc593f9c..bc6b334c4a 100644
--- a/.github/workflows/go.yaml
+++ b/.github/workflows/go.yaml
@@ -36,6 +36,33 @@ jobs:
       - name: Cross build check
         run: make crossbuild
 
+  build-stringlabels:
+    runs-on: ubuntu-latest
+    name: Go build with -tags=stringlabels
+    env:
+      GOBIN: /tmp/.bin
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Install Go
+      uses: actions/setup-go@v5
+      with:
+        go-version: 1.22.x
+
+    - uses: actions/cache@v4
+      with:
+        path: |
+          ~/.cache/go-build
+          ~/.cache/golangci-lint
+          ~/go/pkg/mod
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-
+
+    - name: Cross build check
+      run: go build -tags=stringlabels ./cmd/thanos
+
   lint:
     runs-on: ubuntu-latest
     name: Linters (Static Analysis) for Go
diff --git a/cmd/thanos/config.go b/cmd/thanos/config.go
index a6abd7c3c9..3ce069c1b2 100644
--- a/cmd/thanos/config.go
+++ b/cmd/thanos/config.go
@@ -8,7 +8,6 @@ package main
 
 import (
 	"net/url"
-	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -266,23 +265,23 @@ func (ac *alertMgrConfig) registerFlag(cmd extflag.FlagClause) *alertMgrConfig {
 }
 
 func parseFlagLabels(s []string) (labels.Labels, error) {
-	var lset labels.Labels
+	var lset labels.ScratchBuilder
 	for _, l := range s {
 		parts := strings.SplitN(l, "=", 2)
 		if len(parts) != 2 {
-			return nil, errors.Errorf("unrecognized label %q", l)
+			return labels.EmptyLabels(), errors.Errorf("unrecognized label %q", l)
 		}
 		if !model.LabelName.IsValid(model.LabelName(parts[0])) {
-			return nil, errors.Errorf("unsupported format for label %s", l)
+			return labels.EmptyLabels(), errors.Errorf("unsupported format for label %s", l)
 		}
 		val, err := strconv.Unquote(parts[1])
 		if err != nil {
-			return nil, errors.Wrap(err, "unquote label value")
+			return labels.EmptyLabels(), errors.Wrap(err, "unquote label value")
 		}
-		lset = append(lset, labels.Label{Name: parts[0], Value: val})
+		lset.Add(parts[0], val)
 	}
-	sort.Sort(lset)
-	return lset, nil
+	lset.Sort()
+	return lset.Labels(), nil
 }
 
 type goMemLimitConfig struct {
diff --git a/cmd/thanos/receive.go b/cmd/thanos/receive.go
index 758a0141e8..f10b5be3a3 100644
--- a/cmd/thanos/receive.go
+++ b/cmd/thanos/receive.go
@@ -70,7 +70,7 @@ func registerReceive(app *extkingpin.App) {
 		if !model.LabelName.IsValid(model.LabelName(conf.tenantLabelName)) {
 			return errors.Errorf("unsupported format for tenant label name, got %s", conf.tenantLabelName)
 		}
-		if len(lset) == 0 {
+		if lset.Len() == 0 {
 			return errors.New("no external labels configured for receive, uniquely identifying external labels must be configured (ideally with `receive_` prefix); see https://thanos.io/tip/thanos/storage.md#external-labels for details.")
 		}
 
diff --git a/cmd/thanos/rule.go b/cmd/thanos/rule.go
index da27751345..3fcc452ac6 100644
--- a/cmd/thanos/rule.go
+++ b/cmd/thanos/rule.go
@@ -887,13 +887,7 @@ func removeLockfileIfAny(logger log.Logger, dataDir string) error {
 }
 
 func labelsTSDBToProm(lset labels.Labels) (res labels.Labels) {
-	for _, l := range lset {
-		res = append(res, labels.Label{
-			Name:  l.Name,
-			Value: l.Value,
-		})
-	}
-	return res
+	return lset.Copy()
 }
 
 func queryFuncCreator(
diff --git a/cmd/thanos/sidecar.go b/cmd/thanos/sidecar.go
index 2d51063980..91f7feee54 100644
--- a/cmd/thanos/sidecar.go
+++ b/cmd/thanos/sidecar.go
@@ -253,7 +253,7 @@ func runSidecar(
 				return errors.Wrap(err, "initial external labels query")
 			}
 
-			if len(m.Labels()) == 0 {
+			if m.Labels().Len() == 0 {
 				return errors.New("no external labels configured on Prometheus server, uniquely identifying external labels must be configured; see https://thanos.io/tip/thanos/storage.md#external-labels for details.")
 			}
 			promUp.Set(1)
@@ -393,7 +393,7 @@ func runSidecar(
 			defer cancel()
 
 			if err := runutil.Retry(2*time.Second, extLabelsCtx.Done(), func() error {
-				if len(m.Labels()) == 0 {
+				if m.Labels().Len() == 0 {
 					return errors.New("not uploading as no external labels are configured yet - is Prometheus healthy/reachable?")
 				}
 				return nil
diff --git a/cmd/thanos/tools_bucket.go b/cmd/thanos/tools_bucket.go
index 326e4b09eb..7e711168cf 100644
--- a/cmd/thanos/tools_bucket.go
+++ b/cmd/thanos/tools_bucket.go
@@ -1013,12 +1013,12 @@ func getKeysAlphabetically(labels map[string]string) []string {
 // matchesSelector checks if blockMeta contains every label from
 // the selector with the correct value.
 func matchesSelector(blockMeta *metadata.Meta, selectorLabels labels.Labels) bool {
-	for _, l := range selectorLabels {
-		if v, ok := blockMeta.Thanos.Labels[l.Name]; !ok || v != l.Value {
-			return false
-		}
-	}
-	return true
+	matches := true
+	selectorLabels.Range(func(l labels.Label) {
+		val, ok := blockMeta.Thanos.Labels[l.Name]
+		matches = matches && ok && val == l.Value
+	})
+	return matches
 }
 
 // getIndex calculates the index of s in strs.
diff --git a/pkg/query/endpointset.go b/pkg/query/endpointset.go
index b1faff425b..bf608c74f3 100644
--- a/pkg/query/endpointset.go
+++ b/pkg/query/endpointset.go
@@ -797,11 +797,7 @@ func (er *endpointRef) labelSets() []labels.Labels {
 
 	labelSet := make([]labels.Labels, 0, len(er.metadata.LabelSets))
 	for _, ls := range labelpb.ZLabelSetsToPromLabelSets(er.metadata.LabelSets...) {
-		if len(ls) == 0 {
-			continue
-		}
-		// Compatibility label for Queriers pre 0.8.1. Filter it out now.
-		if ls[0].Name == store.CompatibilityTypeLabelName {
+		if ls.Len() == 0 {
 			continue
 		}
 		labelSet = append(labelSet, ls.Copy())
diff --git a/pkg/query/endpointset_test.go b/pkg/query/endpointset_test.go
index f9955d3412..99db0828a8 100644
--- a/pkg/query/endpointset_test.go
+++ b/pkg/query/endpointset_test.go
@@ -26,7 +26,6 @@ import (
 
 	"github.com/thanos-io/thanos/pkg/component"
 	"github.com/thanos-io/thanos/pkg/info/infopb"
-	"github.com/thanos-io/thanos/pkg/store"
 	"github.com/thanos-io/thanos/pkg/store/labelpb"
 	"github.com/thanos-io/thanos/pkg/store/storepb"
 )
@@ -954,11 +953,6 @@ func TestEndpointSetUpdate_AvailabilityScenarios(t *testing.T) {
 							{Name: "l3", Value: "v4"},
 						},
 					},
-					{
-						Labels: []labelpb.ZLabel{
-							{Name: store.CompatibilityTypeLabelName, Value: "store"},
-						},
-					},
 				}
 			},
 		},
@@ -978,11 +972,6 @@ func TestEndpointSetUpdate_AvailabilityScenarios(t *testing.T) {
 							{Name: "l3", Value: "v4"},
 						},
 					},
-					{
-						Labels: []labelpb.ZLabel{
-							{Name: store.CompatibilityTypeLabelName, Value: "store"},
-						},
-					},
 				}
 			},
 		},