diff --git a/src/reqtraceCmt.ml b/src/reqtraceCmt.ml
index d900403..7cff444 100644
--- a/src/reqtraceCmt.ml
+++ b/src/reqtraceCmt.ml
@@ -16,7 +16,7 @@
  *
  *)
 
-open ReqtraceTypes
+open ReqtraceTypes.Refs
 open Asttypes
 open Parsetree
 open Typedtree
@@ -164,8 +164,8 @@ let read_structure ~rfcs str =
   let module MyIterator = TypedtreeIter.MakeIterator(MyIteratorArgument) in
   MyIterator.iter_structure str;
   {
-    ReqtraceTypes.docs = state.docs;
-    ReqtraceTypes.refs = state.refs;
+    docs = state.docs;
+    refs = state.refs;
   }
 
 
diff --git a/src/reqtraceDocXml.ml b/src/reqtraceDocXml.ml
index 5a92171..4e116bb 100644
--- a/src/reqtraceDocXml.ml
+++ b/src/reqtraceDocXml.ml
@@ -15,7 +15,7 @@
  *
  *)
 
-open ReqtraceTypes
+open ReqtraceTypes.RFC
 
 let xmlns = ""
 
diff --git a/src/reqtraceHtmlCmd.ml b/src/reqtraceHtmlCmd.ml
index e212879..03e06d9 100644
--- a/src/reqtraceHtmlCmd.ml
+++ b/src/reqtraceHtmlCmd.ml
@@ -220,7 +220,7 @@ let render_rfc rfc out_file scheme css =
   let normal_uri = normal_uri ~scheme in
   let uri_of_path = uri_of_path ~scheme in
   let body = Ezxmlm.make_tag "body" ([], []) (*ReqtraceHtml.of_package ~name ~rfc ~normal_uri ~uri_of_path*) in
-  let title = rfc.ReqtraceTypes.title in
+  let title = rfc.ReqtraceTypes.RFC.title in
   write_html ~css ~title out_file body;
   `Ok ()
 
diff --git a/src/reqtraceRefXml.ml b/src/reqtraceRefXml.ml
index d1c4af0..0fe3efd 100644
--- a/src/reqtraceRefXml.ml
+++ b/src/reqtraceRefXml.ml
@@ -16,7 +16,7 @@
  *)
 
 open Ezxmlm
-open ReqtraceTypes
+open ReqtraceTypes.Refs
 
 let ns = "https://github.com/infidel/reqtrace"
 
diff --git a/src/reqtraceTypes.ml b/src/reqtraceTypes.ml
index 65446a0..f464bf9 100644
--- a/src/reqtraceTypes.ml
+++ b/src/reqtraceTypes.ml
@@ -17,30 +17,55 @@
 
 type elemid = string
 
-type linesub = { start_offset: int; end_offset: int; text: string }
-type clause = { id: elemid option; lines: linesub list }
-type paragraph = { id: elemid option; lines: linesub list; clauses: clause list }
-type section = { name: string; id: elemid option; paras: paragraph list; }
-type rfc = { number: int; title: string; sections: section list; }
+module RFC = struct
+  type linesub = {
+    start_offset: int;
+    end_offset: int;
+    text: string;
+  }
 
+  type clause = {
+    id: elemid option;
+    lines: linesub list;
+  }
 
-type docid = RFC of int | Uri of string
+  type paragraph = {
+    id: elemid option;
+    lines: linesub list;
+    clauses: clause list;
+  }
 
-type docbind = string * docid
+  type section = {
+    name: string;
+    id: elemid option;
+    paras: paragraph list;
+  }
 
-type docref = Bound of string | Unbound of docid
+  type rfc = {
+    number: int;
+    title: string;
+    sections: section list;
+  }
+end
 
-type reftype = Impl | Test | Unknown
+module Refs = struct
+  type docid = RFC of int | Uri of string
 
-type reqref = {
-  docref : docref;
-  reqid : string;
-  loc : Location.t;
-  reftype : reftype;
-}
+  type docbind = string * docid
 
-type impl_unit = {
-  docs : docbind list;
-  refs : reqref list;
-}
+  type docref = Bound of string | Unbound of docid
 
+  type reftype = Impl | Test | Unknown
+
+  type reqref = {
+    docref : docref;
+    reqid : string;
+    loc : Location.t;
+    reftype : reftype;
+  }
+
+  type impl_unit = {
+    docs : docbind list;
+    refs : reqref list;
+  }
+end