1 files changed, 5 insertions, 2 deletions
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index 5e8a2523..419a5356 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -1122,8 +1122,11 @@ class btree_iterator : private btree_iterator_generation_info {
   using const_reference = typename params_type::const_reference;
   using slot_type = typename params_type::slot_type;
 
-  using iterator =
-     btree_iterator<normal_node, normal_reference, normal_pointer>;
+  // In sets, all iterators are const.
+  using iterator = absl::conditional_t<
+      is_map_container::value,
+      btree_iterator<normal_node, normal_reference, normal_pointer>,
+      btree_iterator<normal_node, const_reference, const_pointer>>;
   using const_iterator =
       btree_iterator<const_node, const_reference, const_pointer>;