diff --git a/.gitignore b/.gitignore
index c96b8095..d70a36c1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@ bin/sim
 
 data/4.3
 data/5.0
+data/5.1
 
 doc/.yardoc
 doc/*.html