diff --git a/README.md b/README.md
index e1341e0..ff7824f 100644
--- a/README.md
+++ b/README.md
@@ -111,8 +111,8 @@ Attributes will be injected in log payload.
 Other global parameters:
 
 ```go
-slogfiber.TraceIDKey = "trace-id"
-slogfiber.SpanIDKey = "span-id"
+slogfiber.TraceIDKey = "trace_id"
+slogfiber.SpanIDKey = "span_id"
 slogfiber.RequestBodyMaxSize  = 64 * 1024 // 64KB
 slogfiber.ResponseBodyMaxSize = 64 * 1024 // 64KB
 slogfiber.HiddenRequestHeaders = map[string]struct{}{ ... }
diff --git a/middleware.go b/middleware.go
index f69245c..7647d5b 100644
--- a/middleware.go
+++ b/middleware.go
@@ -20,8 +20,8 @@ type customAttributesCtxKeyType struct{}
 var customAttributesCtxKey = customAttributesCtxKeyType{}
 
 var (
-	TraceIDKey   = "trace-id"
-	SpanIDKey    = "span-id"
+	TraceIDKey   = "trace_id"
+	SpanIDKey    = "span_id"
 	RequestIDKey = "id"
 
 	RequestBodyMaxSize  = 64 * 1024 // 64KB