diff --git a/src/core/CCArray.ml b/src/core/CCArray.ml
index 8785019c..eb525f64 100644
--- a/src/core/CCArray.ml
+++ b/src/core/CCArray.ml
@@ -183,7 +183,7 @@ let sort_ranking cmp a =
 *)
 
 (*$Q
-  Q.(array printable_string) (fun a -> \
+  Q.(array_of_size Gen.(0--50) printable_string) (fun a -> \
     let b = sort_ranking String.compare a in \
     let a_sorted = sorted String.compare a in \
     a = Array.map (Array.get a_sorted) b)
diff --git a/src/core/CCArray_slice.ml b/src/core/CCArray_slice.ml
index e8ddac56..fcbe1204 100644
--- a/src/core/CCArray_slice.ml
+++ b/src/core/CCArray_slice.ml
@@ -306,7 +306,7 @@ let sort_ranking cmp a =
 *)
 
 (*$Q
-  Q.(array printable_string) (fun a -> \
+  Q.(array_of_size Gen.(0--50) printable_string) (fun a -> \
   Array.length a > 10 ==> ( Array.length a > 10 && \
   let s = make a 5 ~len:5 in \
   let b = sort_indices String.compare s in \
@@ -325,7 +325,7 @@ let sort_indices cmp a = _sort_indices cmp a.arr a.i a.j
 *)
 
 (*$Q
-  Q.(array printable_string) (fun a -> \
+  Q.(array_of_size Gen.(0--60) printable_string) (fun a -> \
   Array.length a > 10 ==> ( Array.length a > 10 && \
   let s = make a 5 ~len:5 in \
   let b = sort_ranking String.compare s in \
diff --git a/src/threads/CCPool.ml b/src/threads/CCPool.ml
index 2bd4101a..1863e2a8 100644
--- a/src/threads/CCPool.ml
+++ b/src/threads/CCPool.ml
@@ -503,7 +503,7 @@ module Make(P : PARAM) = struct
       let l =
         CCList.(1--10_000)
         |> List.rev_map
-          (fun x-> Fut.make (fun () -> Thread.yield(); fib (x mod 30)))
+          (fun x-> Fut.make (fun () -> Thread.yield(); fib (x mod 20)))
         |> Fut.(map_l (fun x->x>|= fun x->x+1))
       in
       OUnit.assert_bool "not done" (Fut.state l = Waiting);