diff --git a/R/pkg/NAMESPACE b/R/pkg/NAMESPACE
index 239ad065d09ad67696997d19566a59778a20640d..ba386da2aa178636207644dacd8388017b75d0a6 100644
--- a/R/pkg/NAMESPACE
+++ b/R/pkg/NAMESPACE
@@ -185,6 +185,8 @@ exportMethods("%in%",
               "isNaN",
               "isNotNull",
               "isNull",
+              "is.nan",
+              "isnan",
               "kurtosis",
               "lag",
               "last",