diff --git a/src/CsvHelper/CsvWriter.cs b/src/CsvHelper/CsvWriter.cs
index d74da342d..84bde24c5 100644
--- a/src/CsvHelper/CsvWriter.cs
+++ b/src/CsvHelper/CsvWriter.cs
@@ -296,7 +296,7 @@ public virtual void WriteHeader(Type type)
 	/// </summary>
 	/// <param name="record">The header record to write.</param>
 	/// <exception cref="ArgumentNullException">Thrown when no record is passed.</exception>
-	public virtual void WriteDynamicHeader(IDynamicMetaObjectProvider? record)
+	public virtual void WriteDynamicHeader(IDynamicMetaObjectProvider record)
 	{
 		if (record == null)
 		{
@@ -941,3 +941,4 @@ private bool WriteHeaderFromRecord(object? record)
 		return false;
 	}
 }
+