diff --git a/tests/array_reduceRight.ts b/tests/array_reduceRight.ts
index 4e060d8..77ff199 100644
--- a/tests/array_reduceRight.ts
+++ b/tests/array_reduceRight.ts
@@ -1,3 +1,5 @@
+// not own: reduceRight over an array of arrays may start from an element and return it as it is, a
+// second owner of it, which -mm=own refuses by design
 function main() {
 
   const array1 = [