diff --git a/dune-workspace.dev b/dune-workspace.dev
index 90cfb5c4..1c68f94c 100644
--- a/dune-workspace.dev
+++ b/dune-workspace.dev
@@ -1,3 +1,5 @@
+(lang dune 1.0)
+
 ;; This file is used by `make all-supported-ocaml-versions`
 (context (opam (switch 4.02.3)))
 (context (opam (switch 4.03.0)))
diff --git a/src/workspace.ml b/src/workspace.ml
index 0f6ae390..07d9939c 100644
--- a/src/workspace.ml
+++ b/src/workspace.ml
@@ -106,9 +106,13 @@ module Context = struct
       ]
 
   let t ~profile ~x =
-    peek_exn >>= function
-    | List (_, List _ :: _) ->
-      record (Opam.t ~profile ~x) >>| fun x -> Opam x
+    Syntax.get_exn syntax >>= function
+    | (0, _) ->
+      (* jbuild-workspace files *)
+      (peek_exn >>= function
+       | List (_, List _ :: _) ->
+         Sexp.Of_sexp.record (Opam.t ~profile ~x) >>| fun x -> Opam x
+       | _ -> t ~profile ~x)
     | _ -> t ~profile ~x
 
   let name = function