diff --git a/src/action.ml b/src/action.ml
index 0712d136..8b566a32 100644
--- a/src/action.ml
+++ b/src/action.ml
@@ -80,8 +80,9 @@ module Mini_shexp = struct
       | Copy_and_add_line_directive of 'path * 'path
       | System         of 'a
       | Bash           of 'a
-      | Update_file     of 'path * 'a
+      | Update_file    of 'path * 'a
       | Rename         of 'path * 'path
+      | Remove_tree    of 'path
 
     let rec t a p sexp =
       sum
@@ -137,6 +138,7 @@ module Mini_shexp = struct
       | Bash   x -> List [Atom "bash"; f x]
       | Update_file (x, y) -> List [Atom "update-file"; g x; f y]
       | Rename (x, y) -> List [Atom "rename"; g x; g y]
+      | Remove_tree x -> List [Atom "remove-tree"; g x]
 
     let rec fold t ~init:acc ~f =
       match t with
@@ -156,6 +158,7 @@ module Mini_shexp = struct
       | Bash x -> f acc x
       | Update_file (x, y) -> f (f acc x) y
       | Rename (x, y) -> f (f acc x) y
+      | Remove_tree x -> f acc x
 
     let fold_one_step t ~init:acc ~f =
       match t with
@@ -174,7 +177,8 @@ module Mini_shexp = struct
       | System _
       | Bash _
       | Update_file _
-      | Rename _ -> acc
+      | Rename _
+      | Remove_tree _ -> acc
 
     let rec map
       : 'a 'b 'c 'd. ('a, 'b) t -> f1:('a -> 'c) -> f2:('b -> 'd) -> ('c, 'd) t
@@ -203,6 +207,7 @@ module Mini_shexp = struct
         | Bash x -> Bash (f1 x)
         | Update_file (x, y) -> Update_file (f2 x, f1 y)
         | Rename (x, y) -> Rename (f2 x, f2 y)
+        | Remove_tree x -> Remove_tree (f2 x)
   end
   open Ast
 
@@ -277,6 +282,8 @@ module Mini_shexp = struct
       | Update_file (x, y) -> Update_file (expand_path ~dir ~f x, expand_str ~dir ~f y)
       | Rename (x, y) ->
         Rename (expand_path ~dir ~f x, expand_path ~dir ~f y)
+      | Remove_tree x ->
+        Remove_tree (expand_path ~dir ~f x)
   end
 
   open Future
@@ -376,6 +383,9 @@ module Mini_shexp = struct
     | Rename (src, dst) ->
       Unix.rename (Path.to_string src) (Path.to_string dst);
       return ()
+    | Remove_tree path ->
+      Path.rm_rf path;
+      return ()
 
   and redirect outputs fn t ~purpose ~dir ~env ~env_extra ~stdout_to ~stderr_to =
     let fn = Path.to_string fn in
diff --git a/src/action.mli b/src/action.mli
index fc730fa4..f5403961 100644
--- a/src/action.mli
+++ b/src/action.mli
@@ -30,6 +30,7 @@ module Mini_shexp : sig
       | Bash           of 'a
       | Update_file    of 'path * 'a
       | Rename         of 'path * 'path
+      | Remove_tree    of 'path
     val t : 'a Sexp.Of_sexp.t -> 'b Sexp.Of_sexp.t -> ('a, 'b) t Sexp.Of_sexp.t
     val sexp_of_t : 'a Sexp.To_sexp.t -> 'b Sexp.To_sexp.t -> ('a, 'b) t Sexp.To_sexp.t
   end
diff --git a/src/build.ml b/src/build.ml
index d4d0db1b..af8beee6 100644
--- a/src/build.ml
+++ b/src/build.ml
@@ -254,6 +254,10 @@ let symlink ~src ~dst =
 let create_file fn =
   action_context_independent ~targets:[fn] (Create_file fn)
 
+let remove_tree dir =
+  arr (fun _ ->
+    { Action. context = None; action = Remove_tree dir })
+
 let progn ts =
   all ts >>^ fun (actions : Action.t list) ->
   let rec loop context acc actions =
diff --git a/src/build.mli b/src/build.mli
index 732b4d5f..e15dbe30 100644
--- a/src/build.mli
+++ b/src/build.mli
@@ -117,6 +117,7 @@ val copy : src:Path.t -> dst:Path.t -> (unit, Action.t) t
 val symlink : src:Path.t -> dst:Path.t -> (unit, Action.t) t
 
 val create_file : Path.t -> (_, Action.t) t
+val remove_tree : Path.t -> (_, Action.t) t
 
 (** Merge a list of actions *)
 val progn : ('a, Action.t) t list -> ('a, Action.t) t
diff --git a/src/odoc.ml b/src/odoc.ml
index b8fb440b..7d1d6556 100644
--- a/src/odoc.ml
+++ b/src/odoc.ml
@@ -47,7 +47,8 @@ let to_html sctx (m : Module.t) odoc_file ~doc_dir ~odoc ~dir ~includes
      includes
      >>>
      Build.progn
-       [ Build.run ~context ~dir odoc ~extra_targets:[html_file]
+       [ Build.remove_tree html_dir
+       ; Build.run ~context ~dir odoc ~extra_targets:[html_file]
            [ A "html"
            ; Dyn (fun x -> x)
            ; A "-I"; Path dir