diff --git a/src/ZoneCodeGenerator/Parsing/Impl/IncludingStreamFileSystem.cs b/src/ZoneCodeGenerator/Parsing/Impl/IncludingStreamFileSystem.cs
index b899ed9b..c6ab2548 100644
--- a/src/ZoneCodeGenerator/Parsing/Impl/IncludingStreamFileSystem.cs
+++ b/src/ZoneCodeGenerator/Parsing/Impl/IncludingStreamFileSystem.cs
@@ -29,7 +29,7 @@ namespace ZoneCodeGenerator.Parsing.Impl
             public string ReadLine()
             {
                 Line++;
-                return reader.ReadLine();
+                return reader.ReadLine() ?? "";
             }
 
             public void Close()