diff --git a/src/pkg/net/http/request.go b/src/pkg/net/http/request.go
index ccdf121117..57b5d09484 100644
--- a/src/pkg/net/http/request.go
+++ b/src/pkg/net/http/request.go
@@ -291,6 +291,11 @@ func valueOrDefault(value, def string) string {
 	return def
 }
 
+// NOTE: This is not intended to reflect the actual Go version being used.
+// It was changed from "Go http package" to "Go 1.1 package http" at the
+// time of the Go 1.1 release because the former User-Agent had ended up
+// on a blacklist for some intrusion detection systems.
+// See https://codereview.appspot.com/7532043.
 const defaultUserAgent = "Go 1.1 package http"
 
 // Write writes an HTTP/1.1 request -- header and body -- in wire format.