diff --git a/cpp/pmtiles.hpp b/cpp/pmtiles.hpp
index ed64c30..d05a45f 100644
--- a/cpp/pmtiles.hpp
+++ b/cpp/pmtiles.hpp
@@ -5,6 +5,8 @@
 #include <sstream>
 #include <vector>
 #include <tuple>
+#include <functional>
+#include <algorithm>
 
 namespace pmtiles {