diff --git a/.gitignore b/.gitignore
index 84be542c911ed732a1a0b5fe7b6c956218b74007..06b79b9eaf1237bef9b593c00a72fe8ad3e5911a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,3 +17,4 @@ build-dep/
 Makefile.coq
 Makefile.coq.conf
 *.crashcoqide
+_opam