diff --git a/libcxx/test/support/allocators.h b/libcxx/test/support/allocators.h
index 2b987ad872783..02436fd9c35ef 100644
--- a/libcxx/test/support/allocators.h
+++ b/libcxx/test/support/allocators.h
@@ -209,7 +209,7 @@ class MaybePOCCAAllocator {
         : id_(id), copy_assigned_into_(copy_assigned_into) {}
 
     template <class U>
-    MaybePOCCAAllocator(const MaybePOCCAAllocator<U, POCCAValue>& that)
+    TEST_CONSTEXPR MaybePOCCAAllocator(const MaybePOCCAAllocator<U, POCCAValue>& that)
         : id_(that.id_), copy_assigned_into_(that.copy_assigned_into_) {}
 
     MaybePOCCAAllocator(const MaybePOCCAAllocator&) = default;