diff --git a/base.go b/base.go
index ad30998..ec8a8af 100644
--- a/base.go
+++ b/base.go
@@ -147,9 +147,6 @@ type Response struct {
 // ID returns the request identifier for r.
 func (r *Response) ID() string { return r.id }
 
-// SetID sets the request identifier for r. This is for use in proxies.
-func (r *Response) SetID(id string) { r.id = id }
-
 // Error returns a non-nil *Error if the response contains an error.
 func (r *Response) Error() *Error { return r.err }