diff --git a/pdfbox/src/main/java/org/apache/pdfbox/pdfwriter/COSWriter.java b/pdfbox/src/main/java/org/apache/pdfbox/pdfwriter/COSWriter.java
index 26e5a2d5f7d..7c6ed2d31b1 100644
--- a/pdfbox/src/main/java/org/apache/pdfbox/pdfwriter/COSWriter.java
+++ b/pdfbox/src/main/java/org/apache/pdfbox/pdfwriter/COSWriter.java
@@ -803,7 +803,7 @@ private void doWriteXRefTable() throws IOException
     private void fillGapsWithFreeEntries()
     {
         List<NormalXReference> normalXReferences = getXRefEntries().stream() //
-                .filter(e -> e instanceof NormalXReference) //
+                .filter(NormalXReference.class::isInstance) //
                 .map(NormalXReference.class::cast) //
                 .sorted() //
                 .collect(Collectors.toList());