diff --git a/src/plugins/wp/Factory.ml b/src/plugins/wp/Factory.ml
index f35c4a5259648e6f74af522ff9dd1afda81a01a5..668610d8cfccda532eb16e76f332df7ef6875d5a 100644
--- a/src/plugins/wp/Factory.ml
+++ b/src/plugins/wp/Factory.ml
@@ -104,6 +104,9 @@ let describe s =
 (* --- Variable Proxy                                                     --- *)
 (* -------------------------------------------------------------------------- *)
 
+let validity x =
+  if RefUsage.is_nullable x then MemoryContext.Nullable else Valid
+
 module type Proxy = sig
   val datatype : string
   val param : Cil_types.varinfo -> MemoryContext.param
@@ -111,10 +114,6 @@ module type Proxy = sig
     (Cil_types.varinfo -> unit) -> unit
 end
 
-let nullable_status x =
-  if RefUsage.is_nullable x then MemoryContext.Nullable
-  else Valid
-
 module MakeVarUsage(V : Proxy) : MemVar.VarUsage =
 struct
   let datatype = "VarUsage." ^ V.datatype
@@ -128,7 +127,7 @@ struct
     let module S = Datatype.String.Set in
     let open MemoryContext in
     if S.mem x.vname (get_addr ()) then ByAddr else
-    if S.mem x.vname (get_ctxt ()) then InContext (nullable_status x) else
+    if S.mem x.vname (get_ctxt ()) then InContext (validity x) else
     if S.mem x.vname (get_refs ()) then ByRef else
     if S.mem x.vname (get_vars ()) then ByValue else
       V.param x
@@ -186,19 +185,19 @@ let refusage_param ~byref ~context x =
   | RefUsage.NoAccess -> MemoryContext.NotUsed
   | RefUsage.ByAddr -> MemoryContext.ByAddr
   | RefUsage.ByValue ->
-      if context && is_formal_ptr x then
-        MemoryContext.InContext (nullable_status x)
+      if context && is_formal_ptr x then MemoryContext.InContext (validity x)
       else if is_ptr x && not (is_fun_ptr x) then MemoryContext.ByShift
       else MemoryContext.ByValue
   | RefUsage.ByRef ->
       if byref
       then
-        if RefUsage.is_nullable x then MemoryContext.InContext Nullable
+        if RefUsage.is_nullable x
+        then MemoryContext.InContext Nullable
         else MemoryContext.ByRef
       else MemoryContext.ByValue
   | RefUsage.ByArray ->
       if context && is_formal_ptr x
-      then MemoryContext.InArray (nullable_status x)
+      then MemoryContext.InArray (validity x)
       else MemoryContext.ByShift
 
 let refusage_iter ?kf ~init f = RefUsage.iter ?kf ~init (fun x _usage -> f x)