diff --git a/googleApps.ml b/googleApps.ml
index 757a0e6..960cea9 100644
--- a/googleApps.ml
+++ b/googleApps.ml
@@ -45,7 +45,7 @@ include ([%js] : sig
              val set_blob_content_type: blob -> string -> blob [@@js.call "setContentType"]
              val blob_to_js: blob -> Ojs.t
              val get_blob: t -> blob [@@js.call]
-             val set_content: t -> blob [@@js.call]
+             val set_content: t -> string -> t [@@js.call]
            end
 
            module Range : sig
diff --git a/googleApps.mli b/googleApps.mli
index ac815d6..1cf15f7 100644
--- a/googleApps.mli
+++ b/googleApps.mli
@@ -70,7 +70,7 @@ large collection of {!File.t}.*)
  val set_blob_content_type: blob -> string -> blob
  val blob_to_js: blob -> Ojs.t
  val get_blob: t -> blob
- val set_content: t -> blob
+ val set_content: t -> string -> t
 end
 
 (** spreadsheet ranges *)