diff --git a/tracer/span_test.go b/tracer/span_test.go
index e3be14f412..5cb2c14e36 100644
--- a/tracer/span_test.go
+++ b/tracer/span_test.go
@@ -53,6 +53,7 @@ func TestSpanSetMetas(t *testing.T) {
 		"error.msg":   "Something wrong",
 		"error.type":  "*errors.errorString",
 		"status.code": "200",
+		"system.pid":  "29176",
 	}
 	nopMetas := map[string]string{
 		"nopKey1": "nopValue1",