diff --git a/test/dune b/test/dune
index 862beec..ed2584b 100644
--- a/test/dune
+++ b/test/dune
@@ -70,7 +70,7 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:cppo} -V X:123.05.2-alpha.1+foo-2.1 -V COQ:8.13+beta1 %{<}))))
+   (run %{bin:cppo} -V X:123.05.2-alpha.1+foo-2.1 -V COQ:8.13+beta1 -V OCAML:4.12.0~alpha1 %{<}))))
 
 (rule
  (targets test.out)
diff --git a/test/version.cppo b/test/version.cppo
index 4b13350..a7a0224 100644
--- a/test/version.cppo
+++ b/test/version.cppo
@@ -30,3 +30,5 @@ patch: X_PATCH
 #endif
 
 Coq: COQ_VERSION
+
+OCaml pre-release:  OCAML_PRERELEASE
diff --git a/test/version.ref b/test/version.ref
index 0da340f..ea9ca7b 100644
--- a/test/version.ref
+++ b/test/version.ref
@@ -35,3 +35,8 @@ patch:
 Coq: 
 # 32 "version.cppo"
       (8, 13, 0) 
+
+# 34 "version.cppo"
+OCaml pre-release:  
+# 34 "version.cppo"
+                     alpha1