diff --git a/vowpalwabbit/core/include/vw/core/array_parameters_sparse.h b/vowpalwabbit/core/include/vw/core/array_parameters_sparse.h
index 6453626a62d..3fb82ad62fc 100644
--- a/vowpalwabbit/core/include/vw/core/array_parameters_sparse.h
+++ b/vowpalwabbit/core/include/vw/core/array_parameters_sparse.h
@@ -111,7 +111,7 @@ class sparse_parameters
   void share(size_t /* length */);
 #endif
 
-public:
+private:
   // This must be mutable because the const operator[] must be able to intialize default weights to return.
   mutable details::weight_map _map;
   uint64_t _weight_mask;  // (stride*(1 << num_bits) -1)
diff --git a/vowpalwabbit/core/src/array_parameters_sparse.cc b/vowpalwabbit/core/src/array_parameters_sparse.cc
index c824fb16437..b87a4dd7810 100644
--- a/vowpalwabbit/core/src/array_parameters_sparse.cc
+++ b/vowpalwabbit/core/src/array_parameters_sparse.cc
@@ -26,7 +26,7 @@ VW::weight* VW::sparse_parameters::get_or_default_and_get(size_t i) const
   return iter->second.get();
 }
 
-VW::weight* sparse_parameters::get_impl(size_t i) const {
+VW::weight* VW::sparse_parameters::get_impl(size_t i) const {
     static VW::weight default_value = 0.0f;
 
     uint64_t index = i & _weight_mask;