diff --git a/src/core/run.js b/src/core/run.js
index 23ac43e89829fd6e51974db6ac47e4d80755760f..4744b6ae60f1738db57b9738be15651c7d981ec5 100644
--- a/src/core/run.js
+++ b/src/core/run.js
@@ -169,7 +169,7 @@ function run(refs, schema, container) {
             if (sub.oneOf) {
               mix.forEach(omit => {
                 if (omit !== fixed && omit.required) {
-                  omit.required.filter(required => !fixed.required.includes(required)).forEach(function (key) {
+                  omit.required.filter(required => !(fixed.required || []).includes(required)).forEach(function (key) {
                     delete copy.properties[key];
                   });
                 }