diff --git a/OpenRA.Game/FileSystem/ZipFile.cs b/OpenRA.Game/FileSystem/ZipFile.cs
index b396dc43d4..c28036dd80 100644
--- a/OpenRA.Game/FileSystem/ZipFile.cs
+++ b/OpenRA.Game/FileSystem/ZipFile.cs
@@ -98,11 +98,11 @@ namespace OpenRA.FileSystem
 		{
 			readonly MemoryStream pkgStream = new();
 
-			public ReadWriteZipFile(string filename, bool create = false)
+			public ReadWriteZipFile(string filename = null, bool create = false)
 			{
 				// SharpZipLib breaks when asked to update archives loaded from outside streams or files
 				// We can work around this by creating a clean in-memory-only file, cutting all outside references
-				if (!create)
+				if (!string.IsNullOrEmpty(filename) && !create)
 				{
 					using (var copy = new MemoryStream(File.ReadAllBytes(filename)))
 					{
@@ -122,7 +122,8 @@ namespace OpenRA.FileSystem
 
 			void Commit()
 			{
-				File.WriteAllBytes(Name, pkgStream.ToArray());
+				if (!string.IsNullOrEmpty(Name))
+					File.WriteAllBytes(Name, pkgStream.ToArray());
 			}
 
 			public void Update(string filename, byte[] contents)