diff --git a/src/kernel_services/abstract_interp/lmap_sig.mli b/src/kernel_services/abstract_interp/lmap_sig.mli
index fe238921431058ec58b0ee8f8deda27fbe675672..f9c31abc77d4b466d0f36735b2c4c8e310e0ee22 100644
--- a/src/kernel_services/abstract_interp/lmap_sig.mli
+++ b/src/kernel_services/abstract_interp/lmap_sig.mli
@@ -151,7 +151,8 @@ val filter_by_shape: 'a Hptmap.Shape(Base.Base).t -> t -> t
 val remove_base : Base.t -> t -> t
 
 (** [replace_bases substitition map] replaces some bases in [map]
-    according to [substitution]. *)
+    according to [substitution]. If [substitution] conflates different bases,
+    the offsetmaps bound to these bases are joined. *)
 val replace_base: Base.substitution -> t -> t
 
 
diff --git a/src/kernel_services/abstract_interp/locations.mli b/src/kernel_services/abstract_interp/locations.mli
index 5157be7d4edb642bed311dbe52cd716202317830..4bea9a7b4e218c9c6ff972577fbfdf18904a6ae4 100644
--- a/src/kernel_services/abstract_interp/locations.mli
+++ b/src/kernel_services/abstract_interp/locations.mli
@@ -80,7 +80,8 @@ module Location_Bytes : sig
 
   val replace_base: Base.substitution -> t -> bool * t
   (** [replace_base subst loc] changes the location [loc] by substituting the
-      pointed bases according to [subst]. *)
+      pointed bases according to [subst]. If [substitution] conflates different
+      bases, the offsets bound to these bases are joined. *)
 
   val diff : t -> t -> t
     (** Over-approximation of difference. [arg2] needs to be exact or an