diff --git a/include/sec21/memory.h b/include/sec21/memory.h
index 1105eb1..dd7ae6a 100644
--- a/include/sec21/memory.h
+++ b/include/sec21/memory.h
@@ -68,9 +68,14 @@ namespace sec21
    }
 } // namespace sec21
 
+#if __cpp_lib_constexpr_charconv >= 202207L
 template <>
-struct std::formatter<sec21::memory>
+class std::formatter<sec21::memory>
 {
+   bool human_readable{false};
+   std::size_t precision{0};
+
+ public:
    constexpr auto parse(std::format_parse_context& ctx)
    {
       auto pos = ctx.begin();
@@ -78,10 +83,15 @@ struct std::formatter<sec21::memory>
          if (*pos == 'h' or *pos == 'H') {
             human_readable = true;
          }
+#ifndef WIN32
          if (*pos == '.') {
+            //! \todo some issues with MSVC compiler
+            // maybe should work if proposal 'std::from_chars should work with std::string_view' is approved
+            // https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2007r0.html
             pos = std::from_chars(++pos, ctx.end(), precision).ptr;
             --pos;
          }
+#endif
          ++pos;
       }
       return pos;
@@ -90,25 +100,21 @@ struct std::formatter<sec21::memory>
    auto format(sec21::memory const& obj, std::format_context& ctx) const
    {
       constexpr auto units = std::array{"B", "kB", "MB", "GB", "TB", "PB"};
+      auto value = static_cast<double>(obj.bytes);
+      auto unit = units[0];
 
       if (human_readable) {
          constexpr auto factor = 1000;
          //! \todo constexpr auto factorIEC = 1024;
 
-         auto value = static_cast<double>(obj.bytes);
-         auto unit = units[0];
-
          for (decltype(units.size()) i = 0; i < units.size(); ++i) {
             if (obj.bytes >= std::pow(factor, i)) {
                value = static_cast<double>(obj.bytes) / std::pow(factor, i);
                unit = units[i];
             }
          }
-         return std::format_to(ctx.out(), "{:.{}f}{}", value, precision, unit);
       }
-      return std::format_to(ctx.out(), "{}{}", obj.bytes, units[0]);
+      return std::format_to(ctx.out(), "{:.{}f}{}", value, precision, unit);
    }
-
-   bool human_readable{false};
-   std::size_t precision{2};
 };
+#endif
\ No newline at end of file
diff --git a/tests/memory.cpp b/tests/memory.cpp
index d0d25ac..42b5e93 100644
--- a/tests/memory.cpp
+++ b/tests/memory.cpp
@@ -20,7 +20,7 @@ TEST_CASE("memory class", "[sec21]")
    }
    SECTION("test safety check of subtraction operator")
    {
-      REQUIRE_THROWS([] { auto result = memory{2} - memory{10}; }());
+      REQUIRE_THROWS([] { [[maybe_unused]] auto result = memory{2} - memory{10}; }());
       // REQUIRE_THROWS([] { auto result = memory{2} - std::byte{10}; }());
    }
    SECTION("multiplication")
@@ -28,24 +28,35 @@ TEST_CASE("memory class", "[sec21]")
       REQUIRE(memory{2} * memory{1} == 2_B);
       REQUIRE(4_kiB * std::byte{2} == memory{8192});
    }
+#if __cpp_lib_constexpr_charconv >= 202207L
    SECTION("test formatter")
    {
       SECTION("default") { REQUIRE(std::format("{}", memory{1024}) == "1024B"); }
 
       SECTION("format output to a human readable format")
       {
-         REQUIRE(std::format("{:h}", memory{1_kiB}) == "1.02kB");
-         REQUIRE(std::format("{:h}", memory{1_MiB}) == "1.05MB");
-         REQUIRE(std::format("{:h}", memory{1_GiB}) == "1.07GB");
-         REQUIRE(std::format("{:h}", memory{1_TiB}) == "1.10TB");
-         REQUIRE(std::format("{:h}", memory{1_PiB}) == "1.13PB");
+         REQUIRE(std::format("{:h}", memory{1_kiB}) == "1kB");
+         REQUIRE(std::format("{:h}", memory{1_MiB}) == "1MB");
+         REQUIRE(std::format("{:h}", memory{1_GiB}) == "1GB");
+         REQUIRE(std::format("{:h}", memory{1_TiB}) == "1TB");
+         REQUIRE(std::format("{:h}", memory{1_PiB}) == "1PB");
       }
+#ifndef WIN32
       SECTION("human readable format with precision")
       {
          REQUIRE(std::format("{:.0h}", memory{1024 * 1024}) == "1MB");
          REQUIRE(std::format("{:.1h}", memory{1024 * 1024}) == "1.0MB");
+         REQUIRE(std::format("{:.2h}", memory{1024 * 1024}) == "1.05MB");
          REQUIRE(std::format("{:.4h}", memory{1024 * 1024}) == "1.0486MB");
-         REQUIRE(std::format("{:.h}", memory{1024 * 1024}) == "1.05MB");
+         REQUIRE(std::format("{:.h}", memory{1024 * 1024}) == "1MB");
       }
+      SECTION("format with precision")
+      {
+         REQUIRE(std::format("{:.0}", memory{1}) == "1B");
+         REQUIRE(std::format("{:.1}", memory{1}) == "1.0B");
+         REQUIRE(std::format("{:.4}", memory{1}) == "1.0000B");
+      }
+#endif
    }
+#endif
 }