diff --git a/src/format/opamPath.ml b/src/format/opamPath.ml
index 68aea0b63ff..cefd503cc2b 100644
--- a/src/format/opamPath.ml
+++ b/src/format/opamPath.ml
@@ -140,6 +140,8 @@ module Switch = struct
 
   let environment t a = meta t a /- env_filename
 
+  let last_env t a = meta t a / "last-env"
+
   let env_relative_to_prefix pfx = pfx / meta_dirname /- env_filename
 
   let installed_opams t a = meta t a / "packages"
diff --git a/src/format/opamPath.mli b/src/format/opamPath.mli
index 116ed83939a..e6b09dc6354 100644
--- a/src/format/opamPath.mli
+++ b/src/format/opamPath.mli
@@ -174,6 +174,8 @@ module Switch: sig
   (** Cached environment updates. *)
   val environment: t -> switch -> OpamFile.Environment.t OpamFile.t
 
+  val last_env: t -> switch -> dirname
+
   (** Like [environment], but from the switch prefix dir *)
   val env_relative_to_prefix: dirname -> OpamFile.Environment.t OpamFile.t