diff --git a/README.md b/README.md
index 438e297e14803e0675d5a28f342c679ea5633d15..066a865842ea3995ca4d83357ace1fdf116f19d2 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,9 @@ http {
             proxy_pass http://127.0.0.1:8080/backend;
 
             body_filter_by_lua_block {
-                require("tracer"):finish()
+                if ngx.arg[2] then
+                    require("tracer"):finish()
+                end
             }
 
             log_by_lua_block {
diff --git a/examples/nginx.conf b/examples/nginx.conf
index 34005191ffc2676c0d22863f702ec50fc8419642..0eaa3bc9c90bf7827883f1533ccb0a46cc3d67ac 100644
--- a/examples/nginx.conf
+++ b/examples/nginx.conf
@@ -57,7 +57,9 @@ http {
             proxy_pass http://127.0.0.1:8080/tier2/lb;
 
             body_filter_by_lua_block {
-                require("tracer"):finish()
+                if ngx.arg[2] then
+                    require("tracer"):finish()
+                end
             }
 
             log_by_lua_block {
@@ -75,7 +77,9 @@ http {
             proxy_pass http://127.0.0.1:8080/backend;
 
             body_filter_by_lua_block {
-                require("tracer"):finish()
+                if ngx.arg[2] then
+                    require("tracer"):finish()
+                end
             }
 
             log_by_lua_block {