diff --git a/ortac-qcheck-stm.opam b/ortac-qcheck-stm.opam
index 40615842..347dea98 100644
--- a/ortac-qcheck-stm.opam
+++ b/ortac-qcheck-stm.opam
@@ -26,7 +26,7 @@ depends: [
   "cmdliner" {>= "1.1.0"}
   "fmt"
   "ppxlib" {>= "0.26.0"}
-  "mdx" {with-test}
+  "mdx" {with-test & >= "2.3.0"}
   "gospel" {>= "0.2.0"}
   "qcheck-core" {with-test}
   "qcheck-stm" {with-test}