diff --git a/include/boost/static_string/static_string.hpp b/include/boost/static_string/static_string.hpp
index b4d0f31..0eb96d6 100644
--- a/include/boost/static_string/static_string.hpp
+++ b/include/boost/static_string/static_string.hpp
@@ -688,7 +688,7 @@ template<
     typename Traits = std::char_traits<CharT>>
 class basic_static_string 
 #ifndef GENERATING_DOCUMENTATION
-  : detail::optimization_base<N, CharT, Traits>
+  : private detail::optimization_base<N, CharT, Traits>
 #endif
 {
 private:
@@ -701,9 +701,6 @@ private:
     {
         this->term_impl();
     }
-
-    using base = detail::optimization_base<N, CharT, Traits>;
-
 public:
     //--------------------------------------------------------------------------
     //
diff --git a/test/constexpr_tests.hpp b/test/constexpr_tests.hpp
index f83126d..5f4c619 100644
--- a/test/constexpr_tests.hpp
+++ b/test/constexpr_tests.hpp
@@ -193,6 +193,7 @@ testConstantEvaluation()
   a.replace(a.begin(), a.end(), {'a'});
 
 #ifdef BOOST_STATIC_STRING_IS_CONST_EVAL
+  a.clear();
   a.replace(a.begin(), a.end(), "a");
   a.replace(a.begin(), a.end(), "a", 1);
 #endif
@@ -382,6 +383,7 @@ testConstantEvaluation()
   a.replace(a.begin(), a.end(), {'a'});
 
 #ifdef BOOST_STATIC_STRING_IS_CONST_EVAL
+  a.clear();
   a.replace(a.begin(), a.end(), "a");
   a.replace(a.begin(), a.end(), "a", 1);
 #endif