ignore Windows build/test artefacts
diff --git a/.gitignore b/.gitignore
index 5fe9afd..d28a512 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,6 +23,7 @@
 # Test artefacts
 tmp*
 dictionary*
+NUL
 
 # Build artefacts
 projects/