diff --git a/service_map.go b/service_map.go
index f867ec4..963833e 100644
--- a/service_map.go
+++ b/service_map.go
@@ -152,7 +152,7 @@ Loop:
 
 func validateType(t reflect.Type) (rt reflect.Type, rv reflect.Value, err error) {
 	if t.Kind() == reflect.Struct {
-		err = fmt.Errorf("Type is Struct. Pass by reference, i.e. %s", t)
+		err = fmt.Errorf("Type is Struct. Pass by reference, i.e. *%s", t)
 		return
 	}
 	rt = t