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 7d1b035dd..670c90f2d 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/readers/register.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/readers/register.go
@@ -39,6 +39,7 @@ type availableResponse struct {
 	Available bool `json:"available"`
 }
 
+// RegisterAvailable checks if the username is already taken or invalid
 func RegisterAvailable(
 	req *http.Request,
 	accountDB *accounts.Database,