diff --git a/include/mimalloc.h b/include/mimalloc.h
index bce3de93..3e6ba7c3 100644
--- a/include/mimalloc.h
+++ b/include/mimalloc.h
@@ -282,6 +282,7 @@ mi_decl_export int   mi_reserve_os_memory_ex(size_t size, bool commit, bool allo
 mi_decl_export bool  mi_manage_os_memory_ex(void* start, size_t size, bool is_committed, bool is_large, bool is_zero, int numa_node, bool exclusive, mi_arena_id_t* arena_id) mi_attr_noexcept;
 
 #if MI_MALLOC_VERSION >= 200
+// Create a heap that only allocates in the specified arena
 mi_decl_nodiscard mi_decl_export mi_heap_t* mi_heap_new_in_arena(mi_arena_id_t arena_id);
 #endif