diff --git a/README.md b/README.md
index a918dfd..ff6b6f0 100644
--- a/README.md
+++ b/README.md
@@ -587,8 +587,8 @@ For instance if you define the entity filter
 then you might want to get an average over the metrics for those three
 entities. This would be possible by using the `avg` aggregator. The default
 aggregator is `last` which returns only the latest metric point from the
-query. The supported aggregation functions are `avg`, `dev`, `count`,
-`first`, `last`, `max`, `min`, `sum`, `diff`. See the [KariosDB docs](https://kairosdb.github.io/docs/build/html/restapi/Aggregators.html) for
+query. The supported aggregation functions are `avg`, `count`,
+`last`, `max`, `min`, `sum`, `diff`. See the [KariosDB docs](https://kairosdb.github.io/docs/build/html/restapi/Aggregators.html) for
 details.
 
 The `duration` defines the duration used for the timeseries query. E.g. if you
diff --git a/pkg/zmon/zmon.go b/pkg/zmon/zmon.go
index 1501e16..6942d21 100644
--- a/pkg/zmon/zmon.go
+++ b/pkg/zmon/zmon.go
@@ -15,9 +15,7 @@ var (
 	// https://kairosdb.github.io/docs/build/html/restapi/Aggregators.html
 	validAggregators = map[string]struct{}{
 		"avg":   struct{}{},
-		"dev":   struct{}{},
 		"count": struct{}{},
-		"first": struct{}{},
 		"last":  struct{}{},
 		"max":   struct{}{},
 		"min":   struct{}{},
@@ -112,17 +110,10 @@ func (c *Client) Query(checkID int, key string, tags map[string]string, aggregat
 		StartRelative: durationToSampling(duration),
 		Metrics: []metric{
 			{
-				Name:  fmt.Sprintf("zmon.check.%d", checkID),
-				Limit: 10000, // maximum limit of ZMON
-				Tags:  tagsSlice,
-				GroupBy: []tagGroup{
-					{
-						Name: "tag",
-						Tags: []string{
-							"key",
-						},
-					},
-				},
+				Name:        fmt.Sprintf("zmon.check.%d", checkID),
+				Limit:       10000, // maximum limit of ZMON
+				Tags:        tagsSlice,
+				GroupBy:     []tagGroup{},
 				Aggregators: make([]aggregator, 0, len(aggregators)),
 			},
 		},
@@ -142,6 +133,10 @@ func (c *Client) Query(checkID int, key string, tags map[string]string, aggregat
 	// add key to query if defined
 	if key != "" {
 		query.Metrics[0].Tags["key"] = []string{key}
+		query.Metrics[0].GroupBy = append(query.Metrics[0].GroupBy, tagGroup{
+			Name: "tag",
+			Tags: []string{"key"},
+		})
 	}
 
 	body, err := json.Marshal(&query)
@@ -158,6 +153,7 @@ func (c *Client) Query(checkID int, key string, tags map[string]string, aggregat
 
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Accept", "application/json")
+	req.Header.Set("X-Attribution", fmt.Sprintf("kube-metrics-adapter/%d", checkID))
 
 	resp, err := c.http.Do(req)
 	if err != nil {
diff --git a/pkg/zmon/zmon_test.go b/pkg/zmon/zmon_test.go
index f3193b2..938bfe0 100644
--- a/pkg/zmon/zmon_test.go
+++ b/pkg/zmon/zmon_test.go
@@ -1,6 +1,7 @@
 package zmon
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -130,6 +131,37 @@ func TestQuery(tt *testing.T) {
 		tt.Run(ti.msg, func(t *testing.T) {
 			ts := httptest.NewServer(http.HandlerFunc(
 				func(w http.ResponseWriter, r *http.Request) {
+					if ti.status == http.StatusOK {
+						q := metricQuery{}
+						decoder := json.NewDecoder(r.Body)
+						err := decoder.Decode(&q)
+						assert.NoError(t, err)
+
+						numberOfMetrics := len(q.Metrics)
+						assert.Equal(t, 1, numberOfMetrics, "expected 1 metrics, got %d", numberOfMetrics)
+						metric := q.Metrics[0]
+						if ti.key != "" {
+							numberOfTags := len(metric.Tags)
+							assert.Equal(t, 1, numberOfTags, "expected 1 metric, got %d", numberOfTags)
+							tag := metric.Tags["key"][0]
+							assert.Equal(t, ti.key, tag, "expected key '%s' as tag, got '%s'", ti.key, tag)
+
+							numberOfTagGroups := len(metric.GroupBy)
+							assert.Equal(t, 1, numberOfTagGroups, "expected 1 GroupBy tag, got %d", numberOfTagGroups)
+							tagGroups := metric.GroupBy[0]
+
+							numberOfTagGroupTags := len(tagGroups.Tags)
+							assert.Equal(t, 1, numberOfTagGroupTags, "expected 1 GroupBy tag, got %d", numberOfTagGroupTags)
+
+							expectedGroupByTag := "key"
+							groupByTag := tagGroups.Tags[0]
+							assert.Equal(t, expectedGroupByTag, groupByTag, "expected GroupBy tag '%s', got '%s'", expectedGroupByTag, groupByTag)
+						} else {
+							_, ok := metric.Tags["key"]
+							assert.Equal(t, false, ok)
+							assert.Equal(t, 0, len(metric.GroupBy))
+						}
+					}
 					w.WriteHeader(ti.status)
 					_, err := w.Write([]byte(ti.body))
 					assert.NoError(t, err)