diff --git a/config.nix b/config.nix
index afc2ea79ac..7b5a3aeb5b 100644
--- a/config.nix
+++ b/config.nix
@@ -1,4 +1,5 @@
 {
   coq = "8.10";
   mathcomp = "1.11.0+beta1";
+  mathcomp-real-closed = "1.1.0";
 }