diff --git a/devel/dune/Makefile b/devel/dune/Makefile
index f750e656f7c..eb93588c7ba 100644
--- a/devel/dune/Makefile
+++ b/devel/dune/Makefile
@@ -1,13 +1,13 @@
-# $OpenBSD: Makefile,v 1.14 2021/12/19 21:33:27 jca Exp $
+# $OpenBSD: Makefile,v 1.15 2022/01/31 00:04:53 daniel Exp $
 
 MULTI_PACKAGES =	-main -private -configurator
 
 COMMENT-main =		OCaml build system
 COMMENT-private =	private libraries of the dune build system
 COMMENT-configurator =	OCaml library for gathering system configuration
-REVISION-configurator =	1
-REVISION-main =		0
-REVISION-private =	1
+REVISION-configurator =	2
+REVISION-main =		1
+REVISION-private =	2
 
 VERSION =		2.7.0
 
diff --git a/devel/dune/patches/patch-src_dune_cram_exec_ml b/devel/dune/patches/patch-src_dune_cram_exec_ml
new file mode 100644
index 00000000000..a0162b5fe9e
--- /dev/null
+++ b/devel/dune/patches/patch-src_dune_cram_exec_ml
@@ -0,0 +1,17 @@
+$OpenBSD: patch-src_dune_cram_exec_ml,v 1.1 2022/01/31 00:04:53 daniel Exp $
+
+Backport commit for ocaml 4.13 support. see:
+https://github.com/ocaml/dune/commit/c1e82f94aa2883feda752df450130ee204855c09
+
+Index: src/dune/cram_exec.ml
+--- src/dune/cram_exec.ml.orig
++++ src/dune/cram_exec.ml
+@@ -283,7 +283,7 @@ let rewrite_paths build_path_prefix_map ~parent_script
+ 
+ let sanitize ~parent_script cram_to_output :
+     (block_result * metadata_entry * string) Cram_lexer.block list =
+-  List.map cram_to_output ~f:(fun t ->
++  List.map cram_to_output ~f:(fun (t : (block_result * _) Cram_lexer.block) ->
+       match t with
+       | Cram_lexer.Comment t -> Cram_lexer.Comment t
+       | Command