diff --git a/src/React.re b/src/React.re
index e8c9c7fc4..17a7f61b1 100644
--- a/src/React.re
+++ b/src/React.re
@@ -872,14 +872,13 @@ module Uncurried = {
     "useCallback";
 };
 
-type callback('input, 'output) = 'input => 'output;
-
 [@mel.module "react"]
 external useTransition: unit => (bool, callback(callback(unit, unit), unit)) =
   "useTransition";
 
 [@mel.module "react"]
-external startTransition: ([@mel.uncurry] (unit => unit)) => unit = "startTransition";
+external startTransition: ([@mel.uncurry] (unit => unit)) => unit =
+  "startTransition";
 
 [@mel.module "react"]
 external useDebugValue: ('value, ~format: 'value => string=?, unit) => unit =