diff --git a/src/await.ml b/src/await.ml
index bd5e9e759f8..b35c5014fc4 100644
--- a/src/await.ml
+++ b/src/await.ml
@@ -418,12 +418,19 @@ and c_exp' context exp k =
   | NewObjE _ -> exp
 
 and c_block context decs exp k =
-  declare_decs decs (c_decs context decs (meta T.unit (fun _ -> c_exp context exp k)))
+  let is_typ dec =
+    match dec.it with
+    | TypD _ -> true
+    | _ -> false
+  in
+  let (typ_decs,val_decs) = List.partition is_typ decs in
+  blockE typ_decs
+    (declare_decs val_decs (c_decs context val_decs (meta T.unit (fun _ -> c_exp context exp k))))
 
 and c_dec context dec (k:kont) =
   match dec.it with
   | TypD _ ->
-    k -@- unitE
+    assert false
   | LetD (pat,exp) ->
     let patenv,pat' = rename_pat pat in
     let block exp =
@@ -462,7 +469,7 @@ and c_decs context decs k =
 
 and declare_dec dec exp : exp =
   match dec.it with
-  | TypD _ -> exp
+  | TypD _ -> assert false
   | LetD (pat, _) -> declare_pat pat exp
   | VarD (id, exp1) -> declare_id id (T.Mut (typ exp1)) exp
 
diff --git a/src/construct.ml b/src/construct.ml
index df6d17f9901..567dc8a18b9 100644
--- a/src/construct.ml
+++ b/src/construct.ml
@@ -100,6 +100,9 @@ let dec_eff dec = match dec.it with
   | LetD (_,e) | VarD (_,e) -> eff e
 
 let blockE decs exp =
+  match decs with
+  | [] -> exp
+  | _ ->
   let es = List.map dec_eff decs in
   let typ = typ exp in
   let e =  List.fold_left max_eff (eff exp) es in
diff --git a/test/run-dfinity/AST-66.as b/test/run-dfinity/AST-66.as
new file mode 100644
index 00000000000..f54ae2fb10e
--- /dev/null
+++ b/test/run-dfinity/AST-66.as
@@ -0,0 +1,13 @@
+// test cps conversion of async blocks with type decs
+
+let _ = async{
+  type T = Null;
+  await { async (null:T) };
+};
+
+let _ = async{
+  type T = U;
+  let _ = await { async (null:T) };
+  type U = Null;
+  await { async (null:T) };
+};
diff --git a/test/run-dfinity/ok/AST-66.dvm-run.ok b/test/run-dfinity/ok/AST-66.dvm-run.ok
new file mode 100644
index 00000000000..3b7e66c4381
--- /dev/null
+++ b/test/run-dfinity/ok/AST-66.dvm-run.ok
@@ -0,0 +1 @@
+Top-level code done.