diff --git a/src/analyses/commonPriv.ml b/src/analyses/commonPriv.ml
index 7d06844c1b..db75455b40 100644
--- a/src/analyses/commonPriv.ml
+++ b/src/analyses/commonPriv.ml
@@ -60,15 +60,10 @@ struct
     ask.f (Q.MustBeProtectedBy {mutex=m; global=x; write=true; protection})
 
   let protected_vars (ask: Q.ask): varinfo list =
-    let module VS = Set.Make (CilType.Varinfo) in
     Q.AD.fold (fun m acc ->
-        Q.AD.fold (fun l acc ->
-            match l with
-            | Q.AD.Addr.Addr (v,_) -> VS.add v acc (* always `NoOffset from mutex analysis *)
-            | _ -> acc
-          ) (ask.f (Q.MustProtectedVars {mutex = m; write = true})) acc
-      ) (ask.f Q.MustLockset) VS.empty
-    |> VS.elements
+        Q.VS.join (ask.f (Q.MustProtectedVars {mutex = m; write = true})) acc
+      ) (ask.f Q.MustLockset) (Q.VS.empty ())
+    |> Q.VS.elements
 end
 
 module MutexGlobals =
diff --git a/src/analyses/mutexAnalysis.ml b/src/analyses/mutexAnalysis.ml
index 9cc019db76..5a61976ef5 100644
--- a/src/analyses/mutexAnalysis.ml
+++ b/src/analyses/mutexAnalysis.ml
@@ -240,8 +240,8 @@ struct
     | Queries.MustProtectedVars {mutex = m; write} ->
       let protected = GProtected.get ~write Strong (G.protected (ctx.global (V.protected m))) in
       VarSet.fold (fun v acc ->
-          Queries.AD.join (Queries.AD.of_var v) acc
-        ) protected (Queries.AD.empty ())
+          Queries.VS.add v acc
+        ) protected (Queries.VS.empty ())
     | Queries.IterSysVars (Global g, f) ->
       f (Obj.repr (V.protecting g)) (* TODO: something about V.protected? *)
     | WarnGlobal g ->
diff --git a/src/domains/queries.ml b/src/domains/queries.ml
index e51ee90f68..3a0e493640 100644
--- a/src/domains/queries.ml
+++ b/src/domains/queries.ml
@@ -114,7 +114,7 @@ type _ t =
   | CreatedThreads: ConcDomain.ThreadSet.t t
   | MustJoinedThreads: ConcDomain.MustThreadSet.t t
   | ThreadsJoinedCleanly: MustBool.t t
-  | MustProtectedVars: mustprotectedvars -> AD.t t
+  | MustProtectedVars: mustprotectedvars -> VS.t t
   | Invariant: invariant_context -> Invariant.t t
   | InvariantGlobal: Obj.t -> Invariant.t t (** Argument must be of corresponding [Spec.V.t]. *)
   | WarnGlobal: Obj.t -> Unit.t t (** Argument must be of corresponding [Spec.V.t]. *)
@@ -179,7 +179,7 @@ struct
     | CreatedThreads ->  (module ConcDomain.ThreadSet)
     | MustJoinedThreads -> (module ConcDomain.MustThreadSet)
     | ThreadsJoinedCleanly -> (module MustBool)
-    | MustProtectedVars _ -> (module AD)
+    | MustProtectedVars _ -> (module VS)
     | Invariant _ -> (module Invariant)
     | InvariantGlobal _ -> (module Invariant)
     | WarnGlobal _ -> (module Unit)
@@ -243,7 +243,7 @@ struct
     | CreatedThreads -> ConcDomain.ThreadSet.top ()
     | MustJoinedThreads -> ConcDomain.MustThreadSet.top ()
     | ThreadsJoinedCleanly -> MustBool.top ()
-    | MustProtectedVars _ -> AD.top ()
+    | MustProtectedVars _ -> VS.top ()
     | Invariant _ -> Invariant.top ()
     | InvariantGlobal _ -> Invariant.top ()
     | WarnGlobal _ -> Unit.top ()