diff --git a/tracer/tracer.go b/tracer/tracer.go
index de3f6a7e..e2634305 100644
--- a/tracer/tracer.go
+++ b/tracer/tracer.go
@@ -1,10 +1,8 @@
 // Package tracer provides an interface for distributed tracing
-package tracer // import "go.unistack.org/micro/v4/tracer"
+package tracer
 
 import (
 	"context"
-	"fmt"
-	"sort"
 
 	"go.unistack.org/micro/v4/logger"
 	"go.unistack.org/micro/v4/options"
@@ -71,37 +69,3 @@ type Span interface {
 	// SpanID returns span id
 	SpanID() string
 }
-
-// sort labels alphabeticaly by label name
-type byKey []interface{}
-
-func (k byKey) Len() int           { return len(k) / 2 }
-func (k byKey) Less(i, j int) bool { return fmt.Sprintf("%s", k[i*2]) < fmt.Sprintf("%s", k[j*2]) }
-func (k byKey) Swap(i, j int) {
-	k[i*2], k[j*2] = k[j*2], k[i*2]
-	k[i*2+1], k[j*2+1] = k[j*2+1], k[i*2+1]
-}
-
-func UniqLabels(labels []interface{}) []interface{} {
-	if len(labels)%2 == 1 {
-		labels = labels[:len(labels)-1]
-	}
-
-	if len(labels) > 2 {
-		sort.Sort(byKey(labels))
-
-		idx := 0
-		for {
-			if labels[idx] == labels[idx+2] {
-				copy(labels[idx:], labels[idx+2:])
-				labels = labels[:len(labels)-2]
-			} else {
-				idx += 2
-			}
-			if idx+2 >= len(labels) {
-				break
-			}
-		}
-	}
-	return labels
-}
diff --git a/util/sort/sort.go b/util/sort/sort.go
new file mode 100644
index 00000000..d80794b1
--- /dev/null
+++ b/util/sort/sort.go
@@ -0,0 +1,40 @@
+package sort
+
+import (
+	"fmt"
+	"sort"
+)
+
+// sort labels alphabeticaly by label name
+type byKey []interface{}
+
+func (k byKey) Len() int           { return len(k) / 2 }
+func (k byKey) Less(i, j int) bool { return fmt.Sprintf("%s", k[i*2]) < fmt.Sprintf("%s", k[j*2]) }
+func (k byKey) Swap(i, j int) {
+	k[i*2], k[j*2] = k[j*2], k[i*2]
+	k[i*2+1], k[j*2+1] = k[j*2+1], k[i*2+1]
+}
+
+func Uniq(labels []interface{}) []interface{} {
+	if len(labels)%2 == 1 {
+		labels = labels[:len(labels)-1]
+	}
+
+	if len(labels) > 2 {
+		sort.Sort(byKey(labels))
+
+		idx := 0
+		for {
+			if labels[idx] == labels[idx+2] {
+				copy(labels[idx:], labels[idx+2:])
+				labels = labels[:len(labels)-2]
+			} else {
+				idx += 2
+			}
+			if idx+2 >= len(labels) {
+				break
+			}
+		}
+	}
+	return labels
+}