diff --git a/Makefile b/Makefile
index 3d9ebbb..c33757f 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
 MODS = cpdfyojson cpdfxmlm \
        cpdfunicodedata cpdferror cpdfjson cpdfstrftime cpdfcoord cpdfattach \
        cpdfpagespec cpdfposition cpdfpresent cpdfmetadata cpdf cpdffont cpdftype \
-       cpdftexttopdf cpdftoc cpdfpad cpdfocg cpdfsqueeze cpdfcommand
+       cpdftexttopdf cpdftoc cpdfpad cpdfocg cpdfsqueeze cpdfspot cpdfcommand
 
 SOURCES = $(foreach x,$(MODS),$(x).ml $(x).mli) cpdfcommandrun.ml
 
diff --git a/cpdf.ml b/cpdf.ml
index 53ea33c..4a2345c 100644
--- a/cpdf.ml
+++ b/cpdf.ml
@@ -3346,21 +3346,6 @@ let remove_unused_resources_page pdf n page =
 let remove_unused_resources pdf =
   process_pages (ppstub (remove_unused_resources_page pdf)) pdf (ilist 1 (Pdfpage.endpage pdf))
 
-let print_spot_colour n s =
-  Printf.printf "%i %s\n" n s
-
-let list_spot_colours pdf =
-  Pdf.objiter
-    (fun _ obj ->
-       match obj with
-         Pdf.Array (Pdf.Name "/Separation"::x::_) ->
-           begin match Pdf.direct pdf x with
-             Pdf.Name col -> Printf.printf "%s\n" col
-           | _ -> ()
-           end
-       | _ -> ())
-    pdf
-
 (* Indent bookmarks in each file by one and add a title bookmark pointing to the first page. *)
 let add_bookmark_title filename use_title pdf =
   let title =
diff --git a/cpdf.mli b/cpdf.mli
index 5326cac..e65f73a 100644
--- a/cpdf.mli
+++ b/cpdf.mli
@@ -299,8 +299,6 @@ val add_bookmark_title : string -> bool -> Pdf.t -> Pdf.t
 
 val remove_unused_resources : Pdf.t -> Pdf.t
 
-val list_spot_colours : Pdf.t -> unit
-
 val bookmarks_open_to_level : int -> Pdf.t -> Pdf.t
 
 val create_pdf : int -> Pdfpaper.t -> Pdf.t
diff --git a/cpdfcommand.ml b/cpdfcommand.ml
index d1c5a90..e1ec797 100644
--- a/cpdfcommand.ml
+++ b/cpdfcommand.ml
@@ -3831,7 +3831,7 @@ let go () =
         Cpdf.print_dict_entry pdf key
   | Some ListSpotColours ->
       let pdf = get_single_pdf args.op false in
-        Cpdf.list_spot_colours pdf
+        Cpdfspot.list_spot_colours pdf
   | Some RemoveClipping ->
       let pdf = get_single_pdf args.op false in
         let range = parse_pagespec_allow_empty pdf (get_pagespec ()) in
diff --git a/cpdfspot.ml b/cpdfspot.ml
new file mode 100644
index 0000000..44d93a3
--- /dev/null
+++ b/cpdfspot.ml
@@ -0,0 +1,17 @@
+open Pdfutil
+
+let print_spot_colour n s =
+  Printf.printf "%i %s\n" n s
+
+let list_spot_colours pdf =
+  Pdf.objiter
+    (fun _ obj ->
+       match obj with
+         Pdf.Array (Pdf.Name "/Separation"::x::_) ->
+           begin match Pdf.direct pdf x with
+             Pdf.Name col -> Printf.printf "%s\n" col
+           | _ -> ()
+           end
+       | _ -> ())
+    pdf
+
diff --git a/cpdfspot.mli b/cpdfspot.mli
new file mode 100644
index 0000000..2c11426
--- /dev/null
+++ b/cpdfspot.mli
@@ -0,0 +1 @@
+val list_spot_colours : Pdf.t -> unit