diff --git a/js/expression.ml b/js/expression.ml
index bc280436..da4f4a8e 100644
--- a/js/expression.ml
+++ b/js/expression.ml
@@ -3,12 +3,12 @@ open Js_of_ocaml.Js.Unsafe
 
 type t = int
 
-let block wasm_mod name children =
+let block ?(return_type=Type.auto) wasm_mod name children =
   meth_call wasm_mod "block"
     [|
       inject (string name);
       inject (array (Array.of_list children));
-      inject Type.auto;
+      inject return_type;
     |]
 
 let if_ wasm_mod cond if_true if_false =
diff --git a/package.json b/package.json
index fa453386..e716227c 100644
--- a/package.json
+++ b/package.json
@@ -30,7 +30,7 @@
   },
   "scripts": {
     "test": "esy b dune runtest",
-    "format": "dune build @fmt --auto-promote"
+    "format": "esy b dune build @fmt --auto-promote"
   },
   "installConfig": {
     "pnp": false
diff --git a/src/binaryen_stubs_expressions.c b/src/binaryen_stubs_expressions.c
index 6ea702aa..453cdc44 100644
--- a/src/binaryen_stubs_expressions.c
+++ b/src/binaryen_stubs_expressions.c
@@ -22,8 +22,8 @@ caml_binaryen_null_expression(value unit) {
 }
 
 CAMLprim value
-caml_binaryen_block(value _module, value _name, value _children) {
-  CAMLparam3(_module, _name, _children);
+caml_binaryen_block(value _module, value _name, value _children, value _ty) {
+  CAMLparam4(_module, _name, _children, _ty);
   BinaryenModuleRef module = BinaryenModuleRef_val(_module);
   char* name = Safe_String_val(_name);
   _children = array_of_list(_children);
@@ -32,7 +32,8 @@ caml_binaryen_block(value _module, value _name, value _children) {
   for (int i = 0; i < childLen; i++) {
     children[i] = BinaryenExpressionRef_val(Field(_children, i));
   }
-  BinaryenExpressionRef block = BinaryenBlock(module, name, children, childLen, BinaryenTypeAuto());
+  BinaryenType ty = BinaryenType_val(_ty);
+  BinaryenExpressionRef block = BinaryenBlock(module, name, children, childLen, ty);
   CAMLreturn(alloc_BinaryenExpressionRef(block));
 }
 
diff --git a/src/expression.ml b/src/expression.ml
index b5ad7123..cb5ffff9 100644
--- a/src/expression.ml
+++ b/src/expression.ml
@@ -1,6 +1,8 @@
 type t
 
-external block : Module.t -> string -> t list -> t = "caml_binaryen_block"
+external block : Module.t -> string -> t list -> Type.t -> t = "caml_binaryen_block"
+let block ?(return_type=Type.auto) wasm_mod name exprs =
+  block wasm_mod name exprs return_type
 (** Module, block name, expression list. *)
 
 external if_ : Module.t -> t -> t -> t -> t = "caml_binaryen_if"
diff --git a/test/test.expected b/test/test.expected
index 0fafc738..8a1750b5 100644
--- a/test/test.expected
+++ b/test/test.expected
@@ -1,9 +1,11 @@
 (module
  (type $i32_i32_=>_i32 (func (param i32 i32) (result i32)))
  (func $adder (param $0 i32) (param $1 i32) (result i32)
-  (i32.add
-   (local.get $0)
-   (local.get $1)
+  (block $add (result i32)
+   (i32.add
+    (local.get $0)
+    (local.get $1)
+   )
   )
  )
 )
diff --git a/test/test.ml b/test/test.ml
index 48ea9ba3..2d05dcec 100644
--- a/test/test.ml
+++ b/test/test.ml
@@ -12,7 +12,7 @@ let x = Expression.local_get wasm_mod 0 Type.int32
 
 let y = Expression.local_get wasm_mod 1 Type.int32
 
-let add = Expression.binary wasm_mod Op.add_int32 x y
+let add = Expression.block wasm_mod ~return_type:Type.int32 "add" [Expression.binary wasm_mod Op.add_int32 x y]
 
 (* Create the add function *)
 let adder = Function.add_function wasm_mod "adder" params results [||] add
diff --git a/virtual/expression.mli b/virtual/expression.mli
index 9e9f50fd..72220554 100644
--- a/virtual/expression.mli
+++ b/virtual/expression.mli
@@ -1,6 +1,6 @@
 type t
 
-val block : Module.t -> string -> t list -> t
+val block : ?return_type:Type.t -> Module.t -> string -> t list -> t
 
 val if_ : Module.t -> t -> t -> t -> t