diff --git a/csaf/models.go b/csaf/models.go
index ab5bba7..93544bf 100644
--- a/csaf/models.go
+++ b/csaf/models.go
@@ -451,7 +451,7 @@ func NewProviderMetadataDomain(domain string, tlps []TLPLabel) *ProviderMetadata
 
 // WriteTo saves a metadata provider to a writer.
 func (pmd *ProviderMetadata) WriteTo(w io.Writer) (int64, error) {
-	nw := util.NWriter{w, 0}
+	nw := util.NWriter{Writer: w, N: 0}
 	enc := json.NewEncoder(&nw)
 	enc.SetIndent("", "  ")
 	err := enc.Encode(pmd)
diff --git a/csaf/rolie.go b/csaf/rolie.go
index 1451111..f1ab9de 100644
--- a/csaf/rolie.go
+++ b/csaf/rolie.go
@@ -72,7 +72,7 @@ func LoadROLIEFeed(r io.Reader) (*ROLIEFeed, error) {
 
 // WriteTo saves a ROLIE feed to a writer.
 func (rf *ROLIEFeed) WriteTo(w io.Writer) (int64, error) {
-	nw := util.NWriter{w, 0}
+	nw := util.NWriter{Writer: w, N: 0}
 	enc := json.NewEncoder(&nw)
 	enc.SetIndent("", "  ")
 	err := enc.Encode(rf)