diff --git a/tools/src/cmd/cts/common/results.go b/tools/src/cmd/cts/common/results.go
index 934195e..da76147 100644
--- a/tools/src/cmd/cts/common/results.go
+++ b/tools/src/cmd/cts/common/results.go
@@ -218,13 +218,20 @@
 		status := toStatus(rpb.Status)
 		tags := result.NewTags()
 
+		duration := rpb.GetDuration().AsDuration()
+
 		for _, sp := range rpb.Tags {
 			if sp.Key == "typ_tag" {
 				tags.Add(sp.Value)
 			}
+			if sp.Key == "javascript_duration" {
+				var err error
+				if duration, err = time.ParseDuration(sp.Value); err != nil {
+					return err
+				}
+			}
 		}
 
-		duration := rpb.GetDuration().AsDuration()
 		if status == result.Pass && duration > cfg.Test.SlowThreshold {
 			status = result.Slow
 		}