diff --git a/trees/segtree.cc b/trees/segtree.cc
index 74803f8..491ea46 100644
--- a/trees/segtree.cc
+++ b/trees/segtree.cc
@@ -1,6 +1,6 @@
 template<typename T> class segtree {
 private:
-    using size_type = __uint64_t;
+    using size_type = uint64_t;
     T _max;
     vector<T> d, b;