diff --git a/src/PdfSharp/Pdf.Content.Objects/CObjects.cs b/src/PdfSharp/Pdf.Content.Objects/CObjects.cs
index 44308a02..a19f0544 100644
--- a/src/PdfSharp/Pdf.Content.Objects/CObjects.cs
+++ b/src/PdfSharp/Pdf.Content.Objects/CObjects.cs
@@ -771,9 +771,9 @@ public string Name
             get { return _name; }
             set
             {
-                if (String.IsNullOrEmpty(_name))
+                if (String.IsNullOrEmpty(value))
                     throw new ArgumentNullException(nameof(value));
-                if (_name[0] != '/')
+                if (value[0] != '/')
                     throw new ArgumentException(PSSR.NameMustStartWithSlash);
                 _name = value;
             }