diff --git a/pHashtbl.ml b/pHashtbl.ml
index a54fe11b..bbb3b30b 100644
--- a/pHashtbl.ml
+++ b/pHashtbl.ml
@@ -92,7 +92,6 @@ let insert t key value =
       t.buckets.(j) <- Used (key, value, dist)
     | Used (key', _, _) when t.eq key key' ->
       (* insert here (erase old value) *)
-      t.size <- t.size + 1;
       t.buckets.(j) <- Used (key, value, dist)
     | Used (key', value', dist') when dist > dist' ->
       (* displace this key/value *)
@@ -108,7 +107,7 @@ let insert t key value =
 (** Resize the array, by inserting its content into twice as large an array *)
 let resize t =
   let new_size = min (Array.length t.buckets * 2 + 1) Sys.max_array_length in
-  assert (new_size > Array.length t.buckets);
+  if not (new_size > Array.length t.buckets) then failwith "hashtbl is full";
   let old_buckets = t.buckets in
   t.buckets <- Array.make new_size Empty;
   t.size <- 0;  (* will be updated again *)
diff --git a/tests/benchs.ml b/tests/benchs.ml
index d8f6b6ca..5c6d4e9c 100644
--- a/tests/benchs.ml
+++ b/tests/benchs.ml
@@ -16,11 +16,9 @@ let hashtbl_add n =
   h
 
 let _ =
-  let n = 50000 in
-  let res = Bench.bench_funs
+  let res = Bench.bench_n
     ["phashtbl_add", (fun n -> ignore (phashtbl_add n));
      "hashtbl_add", (fun n -> ignore (hashtbl_add n));]
-    n
   in
   Bench.summarize 1. res
 
@@ -29,7 +27,7 @@ let phashtbl_replace n =
   for i = 0 to n do
     PHashtbl.replace h i i;
   done;
-  for i = 0 to n do
+  for i = n downto 0 do
     PHashtbl.replace h i i;
   done;
   h
@@ -39,17 +37,15 @@ let hashtbl_replace n =
   for i = 0 to n do
     Hashtbl.replace h i i;
   done;
-  for i = 0 to n do
+  for i = n downto 0 do
     Hashtbl.replace h i i;
   done;
   h
 
 let _ =
-  let n = 50000 in
-  let res = Bench.bench_funs
+  let res = Bench.bench_n
     ["phashtbl_replace", (fun n -> ignore (phashtbl_replace n));
      "hashtbl_replace", (fun n -> ignore (hashtbl_replace n));]
-    n
   in
   Bench.summarize 1. res