diff --git a/core/trace/tracespec/vars.go b/core/trace/tracespec/vars.go
index 35a2ee18..6150800a 100644
--- a/core/trace/tracespec/vars.go
+++ b/core/trace/tracespec/vars.go
@@ -1,3 +1,7 @@
 package tracespec
 
-const TracingKey = "X-Trace"
+//ContextKey a type for context key
+type ContextKey struct{}
+
+//TracingKey is tracing key for ctx
+var TracingKey ContextKey