diff --git a/.gitignore b/.gitignore
index f4de0430509eeaeaafb7c73827e3c803a8572ce1..28f56a335bf0cba0b203df8156fbed41a88d898a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ Makefile.coq.conf
 *.crashcoqide
 html/
 build-dep/
+_opam