diff --git a/.gitignore b/.gitignore
index 36d762ba4dc5ea2b154c2c91de4663543b4db9a7..db187c816131a6b7827c84d29602c93513cb3c4f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@
 build-dep/
 Makefile.coq
 Makefile.coq.conf
+_opam