diff --git a/NAMESPACE b/NAMESPACE
index add034b..8c76b79 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -40,8 +40,10 @@ importFrom(quadprog,solve.QP)
 importFrom(stats,approx)
 importFrom(stats,density)
 importFrom(stats,median)
+importFrom(stats,model.matrix)
 importFrom(stats,predict)
 importFrom(stats,quantile)
+importFrom(stats,sd)
 importFrom(stats,update)
 importFrom(utils,str)
 useDynLib(densityratio, .registration = TRUE)