diff --git a/Porthos/.gitignore b/Porthos/.gitignore
index e30286ace5eb8eb13492b7ba553f445e2aefc445..778019bc9cdfe607a502d2f7bbfadbdd8a279a29 100644
--- a/Porthos/.gitignore
+++ b/Porthos/.gitignore
@@ -3,3 +3,4 @@ util/Miracl/
 **/*.out
 *.log
 **/*.swp
+lib_eigen/