diff --git a/src/core/CCList.ml b/src/core/CCList.ml
index e8b5be45..87c7fefc 100644
--- a/src/core/CCList.ml
+++ b/src/core/CCList.ml
@@ -151,6 +151,12 @@ let cons_maybe o l =
   | Some x -> x :: l
   | None -> l
 
+let cons_when b x l =
+  if b then
+    x :: l
+  else
+    l
+
 [@@@iflt 4.14]
 
 let direct_depth_filter_ = 10_000
diff --git a/src/core/CCList.mli b/src/core/CCList.mli
index 865dca79..4f54dbb3 100644
--- a/src/core/CCList.mli
+++ b/src/core/CCList.mli
@@ -25,6 +25,11 @@ val cons_maybe : 'a option -> 'a t -> 'a t
     [cons_maybe None l] is [l].
     @since 0.13 *)
 
+val cons_when : bool -> 'a -> 'a t -> 'a t
+(** [cons_when true x l] is [x :: l].
+    [cons_when false x l] is [l].
+    @since NEXT_RELEASE *)
+
 val cons' : 'a t -> 'a -> 'a t
 (** [cons' l x] is the same as [x :: l]. This is convenient for fold
     functions such as {!List.fold_left} or {!Array.fold_left}.