diff --git a/src/net/http/request.go b/src/net/http/request.go
index da5ac2c71b..8afe1a7c0c 100644
--- a/src/net/http/request.go
+++ b/src/net/http/request.go
@@ -912,6 +912,10 @@ func parseBasicAuth(auth string) (username, password string, ok bool) {
 //
 // With HTTP Basic Authentication the provided username and password
 // are not encrypted.
+//
+// Some protocols may impose additional requirements on pre-escaping the
+// username and password. For instance, when used with OAuth2, both arguments
+// must be URL encoded first with url.QueryEscape.
 func (r *Request) SetBasicAuth(username, password string) {
 	r.Header.Set("Authorization", "Basic "+basicAuth(username, password))
 }