diff --git a/packages/core/value.mjs b/packages/core/value.mjs
index 878e6b1f..62bd4fbb 100644
--- a/packages/core/value.mjs
+++ b/packages/core/value.mjs
@@ -1,6 +1,6 @@
 import { curry } from './util.mjs';
 
-function unionWithObj(a, b, func) {
+export function unionWithObj(a, b, func) {
   const common = Object.keys(a).filter((k) => Object.keys(b).includes(k));
   return Object.assign({}, a, b, Object.fromEntries(common.map((k) => [k, func(a[k], b[k])])));
 }