diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.pass.cpp
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.pass.cpp
@@ -571,6 +571,7 @@
 
 int main(int, char**) {
   test_iterators_in1_in2<cpp17_output_iterator<int*>>();
+  test_iterators_in1_in2<cpp20_output_iterator<int*>>();
   test_iterators_in1_in2<forward_iterator<int*>>();
   test_iterators_in1_in2<bidirectional_iterator<int*>>();
   test_iterators_in1_in2<random_access_iterator<int*>>();