diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 4777205d..572c3598 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -119,10 +119,20 @@ let clear_and_reset v =
 
 let[@inline] is_empty v = v.size = 0
 
+[@@@ifge 4.13]
+
 let[@inline] push_unsafe_ v x =
+  Sys.opaque_identity (Array.unsafe_set v.vec v.size x);
+  v.size <- v.size + 1
+
+[@@@else_]
+
+let[@inline never] push_unsafe_ v x =
   Array.unsafe_set v.vec v.size x;
   v.size <- v.size + 1
 
+[@@@endif]
+
 let push v x =
   if v.size = Array.length v.vec then grow_with_ v ~filler:x;
   push_unsafe_ v x
@@ -174,6 +184,8 @@ let append a b =
     a.size <- a.size + b.size
   )
 
+[@@@ifge 4.13]
+
 let[@inline] get v i =
   if i < 0 || i >= v.size then invalid_arg "CCVector.get";
   (* NOTE: over eager inlining seems to miscompile for int32 at least (#454) *)
@@ -183,6 +195,18 @@ let[@inline] set v i x =
   if i < 0 || i >= v.size then invalid_arg "CCVector.set";
   Array.unsafe_set v.vec i x
 
+[@@@else_]
+
+let[@inline never] get v i =
+  if i < 0 || i >= v.size then invalid_arg "CCVector.get";
+  Array.unsafe_get v.vec i
+
+let[@inline never] set v i x =
+  if i < 0 || i >= v.size then invalid_arg "CCVector.set";
+  Array.unsafe_set v.vec i x
+
+[@@@endif]
+
 let remove_and_shift v i =
   if i < 0 || i >= v.size then invalid_arg "CCVector.remove";
   (* if v.(i) not the last element, then put last element at index i *)