diff --git a/src/types/AbstractType.js b/src/types/AbstractType.js
index 1f4f04dd..59484d31 100644
--- a/src/types/AbstractType.js
+++ b/src/types/AbstractType.js
@@ -1045,6 +1045,7 @@ export const typeListInsertGenericsAfter = (transaction, parent, referenceItem,
       switch (c.constructor) {
         case Number:
         case Object:
+        case undefined:
         case Boolean:
         case Array:
         case String: