diff --git a/benchs/run_benchs.ml b/benchs/run_benchs.ml
index ca50ad18..d22a820a 100644
--- a/benchs/run_benchs.ml
+++ b/benchs/run_benchs.ml
@@ -97,6 +97,15 @@ module L = struct
     else
       Sek.Persistent.of_list 0 [ x; x + 1; x + 2; x + 3 ]
 
+
+  let f_pvec x =
+    if x mod 10 = 0 then
+      Pvec.empty
+    else if x mod 5 = 1 then
+      Pvec.of_list [ x; x + 1 ]
+    else
+      Pvec.of_list [ x; x + 1; x + 2; x + 3 ]
+
   let flat_map_kont f l =
     let rec aux f l kont =
       match l with
@@ -118,6 +127,7 @@ module L = struct
     let l = CCList.(1 -- n) in
     let ral = CCRAL.of_list l in
     let sek = Sek.Persistent.of_list 0 l in
+    let pvec = Pvec.of_list l in
     let flatten_map_ l () =
       ignore @@ Sys.opaque_identity @@ List.flatten (CCList.map f_ l)
     and flatmap_kont l () = ignore @@ Sys.opaque_identity @@ flat_map_kont f_ l
@@ -128,6 +138,8 @@ module L = struct
       ignore @@ Sys.opaque_identity @@ CCRAL.flat_map f_ral_ l
     and flatmap_sek s () =
       ignore @@ Sys.opaque_identity @@ Sek.Persistent.flatten_map 0 f_sek_ s
+    and flat_map_pvec v () =
+      ignore @@ Sys.opaque_identity @@ Pvec.flat_map f_pvec v
     in
     B.throughputN time ~repeat
       [
@@ -137,6 +149,7 @@ module L = struct
         "flatten o map", flatten_map_ l, ();
         "ral_flatmap", flatmap_ral_ ral, ();
         "sek_flatmap", flatmap_sek sek, ();
+        "pvec.flatmap", flat_map_pvec pvec, ()
       ]
 
   (* APPEND *)
diff --git a/src/pvec/containers_pvec.mli b/src/pvec/containers_pvec.mli
index 2c3bd25e..52a9e8b2 100644
--- a/src/pvec/containers_pvec.mli
+++ b/src/pvec/containers_pvec.mli
@@ -86,7 +86,9 @@ val append : 'a t -> 'a t -> 'a t
 val map : ('a -> 'b) -> 'a t -> 'b t
 
 val flat_map : ('a -> 'b t) -> 'a t -> 'b t
-(** @since NEXT_RELEASE *)
+(** A basic, fairly slow [flat_map] operation like {!CCList.flat_map}.
+    It exists for convenience but is not where this data structure shines.
+    @since NEXT_RELEASE *)
 
 val choose : 'a t -> 'a option
 (** Return an element. It is unspecified which one is returned. *)