diff --git a/tree/ntuple/v7/inc/ROOT/RPageStorageDaos.hxx b/tree/ntuple/v7/inc/ROOT/RPageStorageDaos.hxx
index 748a71f8d0643b778a914e1a9ce6110fd7ecae93..8e701a230f6d15d17de133a23f555b5aebcb6160 100644
--- a/tree/ntuple/v7/inc/ROOT/RPageStorageDaos.hxx
+++ b/tree/ntuple/v7/inc/ROOT/RPageStorageDaos.hxx
@@ -115,8 +115,8 @@ struct RDaosContainerNTupleLocator {
    static ntuple_index_t Hash(const std::string &ntupleName)
    {
       // Convert string to numeric representation via `std::hash`.
-      std::size_t h = std::hash<std::string>{}(ntupleName);
-      // Fold `std::size_t` bits into 32-bit using `boost::hash_combine()` algorithm and magic number.
+      uint64_t h = std::hash<std::string>{}(ntupleName);
+      // Fold the hash into 32-bit using `boost::hash_combine()` algorithm and magic number.
       auto seed = static_cast<uint32_t>(h >> 32);
       seed ^= static_cast<uint32_t>(h & 0xffffffff) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
       auto hash = static_cast<ntuple_index_t>(seed);