diff --git a/panel.go b/panel.go
index <HASH>..<HASH> 100644
--- a/panel.go
+++ b/panel.go
@@ -566,7 +566,7 @@ type Target struct {
 	CrossSeriesReducer string                    `json:"crossSeriesReducer,omitempty"`
 	PerSeriesAligner   string                    `json:"perSeriesAligner,omitempty"`
 	ValueType          string                    `json:"valueType,omitempty"`
-	GroupBys           []string                  `json:"groupBys,omitempty"`
+	GroupBy            []string                  `json:"groupBy,omitempty"`
 	Tags               []struct {
 		Key      string `json:"key,omitempty"`
 		Operator string `json:"operator,omitempty"`
diff --git a/panel_test.go b/panel_test.go
index <HASH>..<HASH> 100644
--- a/panel_test.go
+++ b/panel_test.go
@@ -630,7 +630,7 @@ func TestPanel_Stackdriver_ParsedTargets(t *testing.T) {
 		"=",
 		"some_subscription_id"
 	  ],
-	  "groupBys": [],
+	  "groupBy": [],
 	  "metricKind": "DELTA",
 	  "metricType": "pubsub.googleapis.com/subscription/ack_message_count",
 	  "perSeriesAligner": "ALIGN_DELTA",
🐛: Target.GroupBy should be singular in the type declaration (#<I>)

* GroupBy should be singular in the JSON



* fix json declaration for groupBy