diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index fcfd4c87..05f61ea7 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -165,6 +165,14 @@ let append a b =
 (*$T
   let v1 = init 5 (fun i->i) and v2 = init 5 (fun i->i+5) in \
   append v1 v2; to_list v1 = CCList.(0--9)
+  let empty = create () and v2 = init 5 (fun i->i) in \
+  append empty v2; to_list empty = CCList.(0--4)
+  let v1 = init 5 (fun i->i) and empty = create () in \
+  append v1 empty; to_list v1 = CCList.(0--4)
+  let v = init 3 (fun i->i) in \
+  append v v; to_list v = [0; 1; 2; 0; 1; 2]
+  let empty = create () in \
+  append empty empty; to_list empty = []
 *)
 
 (*$R
@@ -204,6 +212,12 @@ let append_array a b =
 (*$T
   let v1 = init 5 (fun i->i) and v2 = Array.init 5 (fun i->i+5) in \
   append_array v1 v2; to_list v1 = CCList.(0--9)
+  let empty = create () in \
+  append_array empty CCArray.(0--5); to_list empty = CCList.(0--5)
+  let v1 = init 5 (fun i->i) in \
+  append_array v1 [| |]; to_list v1 = CCList.(0--4)
+  let empty = create () in \
+  append_array empty [| |]; to_list empty = []
 *)
 
 let append_list a b = match b with