diff --git a/pkg/services/alerting/conditions/reducer.go b/pkg/services/alerting/conditions/reducer.go
index 81078b601e4..6eaa21b958e 100644
--- a/pkg/services/alerting/conditions/reducer.go
+++ b/pkg/services/alerting/conditions/reducer.go
@@ -117,7 +117,7 @@ func (s *SimpleReducer) Reduce(series *tsdb.TimeSeries) null.Float {
 				break
 			}
 		}
-	case "pdiff":
+	case "percent_diff":
 		var (
 			points = series.Points
 			first  float64
diff --git a/pkg/services/alerting/conditions/reducer_test.go b/pkg/services/alerting/conditions/reducer_test.go
index 686a5b85478..f0147e9021a 100644
--- a/pkg/services/alerting/conditions/reducer_test.go
+++ b/pkg/services/alerting/conditions/reducer_test.go
@@ -86,8 +86,8 @@ func TestSimpleReducer(t *testing.T) {
 			So(result, ShouldEqual, float64(10))
 		})
 
-		Convey("pdiff", func() {
-			result := testReducer("pdiff", 30, 40)
+		Convey("percent_diff", func() {
+			result := testReducer("percent_diff", 30, 40)
 			So(result, ShouldEqual, float64(33.33333333333333))
 		})
 
diff --git a/public/app/features/alerting/alert_def.ts b/public/app/features/alerting/alert_def.ts
index cf6585bb6c6..51cbbd9691f 100644
--- a/public/app/features/alerting/alert_def.ts
+++ b/public/app/features/alerting/alert_def.ts
@@ -50,7 +50,7 @@ var reducerTypes = [
   {text: 'last()', value: 'last'},
   {text: 'median()', value: 'median'},
   {text: 'diff()', value: 'diff'},
-  {text: 'pdiff()', value: 'pdiff'},
+  {text: 'percent_diff()', value: 'percent_diff'},
 ];
 
 var noDataModes = [