diff --git a/src/github.com/matrix-org/dendrite/clientapi/readers/register.go b/src/github.com/matrix-org/dendrite/clientapi/readers/register.go
index 670c90f2d..f1a35d4d2 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/readers/register.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/readers/register.go
@@ -46,13 +46,6 @@ func RegisterAvailable(
 ) util.JSONResponse {
 	username := req.URL.Query().Get("username")
 
-	if username == "" {
-		return util.JSONResponse{
-			Code: 400,
-			JSON: jsonerror.InvalidUsername("Missing query parameter"),
-		}
-	}
-
 	if resErr := validate(username); resErr != nil {
 		return *resErr
 	}