diff --git a/unittests/structs_minimal.cpp b/unittests/structs_minimal.cpp
index 5dfbf660..877c65f6 100644
--- a/unittests/structs_minimal.cpp
+++ b/unittests/structs_minimal.cpp
@@ -169,6 +169,41 @@ void load_minimal( Archive const &, Issue79Struct & val, std::int32_t const & xx
   val.x = xx;
 }
 
+struct Issue79StructInternal
+{
+  Issue79StructInternal() = default;
+  Issue79StructInternal( std::int32_t xx ) : x(xx) {}
+  std::int32_t x;
+
+  template <class Archive, cereal::traits::DisableIf<std::is_same<Archive, cereal::BinaryOutputArchive>::value ||
+                                                     std::is_same<Archive, cereal::PortableBinaryOutputArchive>::value> = cereal::traits::sfinae>
+  std::string save_minimal( Archive const & ) const
+  {
+    return std::to_string( x );
+  }
+
+  template <class Archive, cereal::traits::DisableIf<std::is_same<Archive, cereal::BinaryInputArchive>::value ||
+                                                     std::is_same<Archive, cereal::PortableBinaryInputArchive>::value> = cereal::traits::sfinae>
+  void load_minimal( Archive const &, std::string const & str )
+  {
+    x = std::stoi( str );
+  }
+
+  template <class Archive, cereal::traits::EnableIf<std::is_same<Archive, cereal::BinaryOutputArchive>::value ||
+                                                    std::is_same<Archive, cereal::PortableBinaryOutputArchive>::value> = cereal::traits::sfinae>
+  std::int32_t save_minimal( Archive const & ) const
+  {
+    return x;
+  }
+
+  template <class Archive, cereal::traits::EnableIf<std::is_same<Archive, cereal::BinaryInputArchive>::value ||
+                                                    std::is_same<Archive, cereal::PortableBinaryInputArchive>::value> = cereal::traits::sfinae>
+  void load_minimal( Archive const &, std::int32_t const & xx )
+  {
+    x = xx;
+  }
+};
+
 template <class IArchive, class OArchive>
 void test_structs_minimal()
 {
@@ -181,22 +216,26 @@ void test_structs_minimal()
                             random_value<std::uint32_t>(gen), random_value<uint8_t>(gen) % 2 ? true : false };
 
     Issue79Struct o_struct2 = { random_value<std::int32_t>(gen) };
+    Issue79StructInternal o_struct3 = { random_value<std::int32_t>(gen) };
 
     std::ostringstream os;
     {
       OArchive oar(os);
       oar( o_struct );
       oar( o_struct2 );
+      oar( o_struct3 );
     }
 
     decltype(o_struct) i_struct;
     decltype(o_struct2) i_struct2;
+    decltype(o_struct3) i_struct3;
 
     std::istringstream is(os.str());
     {
       IArchive iar(is);
       iar( i_struct );
       iar( i_struct2 );
+      iar( i_struct3 );
     }
 
     BOOST_CHECK(o_struct.mm.x == i_struct.mm.x);
@@ -206,6 +245,8 @@ void test_structs_minimal()
     BOOST_CHECK(o_struct.nmmv.x == i_struct.nmmv.x);
 
     BOOST_CHECK(o_struct2.x == i_struct2.x);
+
+    BOOST_CHECK(o_struct3.x == i_struct3.x);
   }
 }