diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0038417bb7..ece71157099 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
     - Routing:
       - FIXED: Fix generation of inefficient MLD partitions [#6084](https://github.com/Project-OSRM/osrm-backend/pull/6084)
       - FIXED: Fix MLD level mask generation to support 64-bit masks. [#6123](https://github.com/Project-OSRM/osrm-backend/pull/6123)
+      - FIXED: Fix metric offset overflow for large MLD partitions. This breaks the **data format** [#6124](https://github.com/Project-OSRM/osrm-backend/pull/6124)
 
 # 5.25.0
   - Changes from 5.24.0
diff --git a/include/partitioner/cell_storage.hpp b/include/partitioner/cell_storage.hpp
index 42c347861d2..c2331f316ba 100644
--- a/include/partitioner/cell_storage.hpp
+++ b/include/partitioner/cell_storage.hpp
@@ -52,11 +52,9 @@ namespace detail
 template <storage::Ownership Ownership> class CellStorageImpl
 {
   public:
-    using ValueOffset = std::uint32_t;
-    using BoundaryOffset = std::uint32_t;
+    using ValueOffset = std::uint64_t;
+    using BoundaryOffset = std::uint64_t;
     using BoundarySize = std::uint32_t;
-    using SourceIndex = std::uint32_t;
-    using DestinationIndex = std::uint32_t;
 
     static constexpr auto INVALID_VALUE_OFFSET = std::numeric_limits<ValueOffset>::max();
     static constexpr auto INVALID_BOUNDARY_OFFSET = std::numeric_limits<BoundaryOffset>::max();