diff --git a/src/core/CCHeap.mli b/src/core/CCHeap.mli
index 243b7b98..5cd427d9 100644
--- a/src/core/CCHeap.mli
+++ b/src/core/CCHeap.mli
@@ -1,7 +1,9 @@
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
-(** {1 Leftist Heaps} following Okasaki *)
+(** {1 Leftist Heaps}
+    
+    Implementation following Okasaki's book. *)
 
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
diff --git a/src/data/CCFun_vec.mli b/src/data/CCFun_vec.mli
index 76f907f3..bff63d96 100644
--- a/src/data/CCFun_vec.mli
+++ b/src/data/CCFun_vec.mli
@@ -106,7 +106,7 @@ val choose : 'a t -> 'a option
    val append_mut : id:Transient.t -> into:'a t -> 'a t -> 'a t
 *)
 
-(** {6 Conversions} *)
+(** {5 Conversions} *)
 
 val to_list : 'a t -> 'a list
 
@@ -138,6 +138,6 @@ val to_gen : 'a t -> 'a gen
    (** @raise Frozen if the ID is frozen. *)
 *)
 
-(** {6 IO} *)
+(** {5 IO} *)
 
 val pp : 'a printer -> 'a t printer
diff --git a/src/data/CCHashTrie.mli b/src/data/CCHashTrie.mli
index 70f84632..2fb1a728 100644
--- a/src/data/CCHashTrie.mli
+++ b/src/data/CCHashTrie.mli
@@ -107,7 +107,7 @@ module type S = sig
 
   val fold : f:('b -> key -> 'a -> 'b) -> x:'b -> 'a t -> 'b
 
-  (** {6 Conversions} *)
+  (** {5 Conversions} *)
 
   val to_list : 'a t -> (key * 'a) list
 
@@ -136,7 +136,7 @@ module type S = sig
 
   val to_gen : 'a t -> (key * 'a) gen
 
-  (** {6 IO} *)
+  (** {5 IO} *)
 
   val pp : key printer -> 'a printer -> 'a t printer
   (** Renamed from [val print].