diff --git a/clients/sfizz_render.cpp b/clients/sfizz_render.cpp
index 1affaf633..1991a7c89 100644
--- a/clients/sfizz_render.cpp
+++ b/clients/sfizz_render.cpp
@@ -3,6 +3,7 @@
 #include "sfizz/MathHelpers.h"
 #include "sfizz/SfzHelpers.h"
 #include "sfizz/SIMDHelpers.h"
+#include "sfizz/utility/U8Strings.h"
 #include "MidiHelpers.h"
 #include <st_audiofile_libs.h>
 #include <cxxopts.hpp>
@@ -165,7 +166,7 @@ int main(int argc, char** argv)
     ERROR_IF(!synth.loadSfzFile(sfzPath), "There was an error loading the SFZ file.");
     LOG_INFO(synth.getNumRegions() << " regions in the SFZ.");
 
-    fmidi_smf_u midiFile { fmidi_smf_file_read(midiPath.u8string().c_str()) };
+    fmidi_smf_u midiFile { fmidi_smf_file_read(u8EncodedString(midiPath).c_str()) };
     ERROR_IF(!midiFile, "Can't read " << midiPath);
 
     const auto* midiInfo = fmidi_smf_get_info(midiFile.get());
diff --git a/external/threadpool/ThreadPool.h b/external/threadpool/ThreadPool.h
index 2e030687c..19b519b38 100644
--- a/external/threadpool/ThreadPool.h
+++ b/external/threadpool/ThreadPool.h
@@ -18,7 +18,11 @@ class ThreadPool {
     ThreadPool(size_t);
     template<class F, class... Args>
     auto enqueue(F&& f, Args&&... args)
+#if __cplusplus >= 201703L
+        -> std::future<typename std::invoke_result<F, Args...>::type>;
+#else
         -> std::future<typename std::result_of<F(Args...)>::type>;
+#endif
     ~ThreadPool();
 private:
     // need to keep track of threads so we can join them
@@ -63,9 +67,17 @@ inline ThreadPool::ThreadPool(size_t threads)
 // add new work item to the pool
 template<class F, class... Args>
 auto ThreadPool::enqueue(F&& f, Args&&... args)
+#if __cplusplus >= 201703L
+    -> std::future<typename std::invoke_result<F, Args...>::type>
+#else
     -> std::future<typename std::result_of<F(Args...)>::type>
+#endif
 {
+#if __cplusplus >= 201703L
+    using return_type = typename std::invoke_result<F, Args...>::type;
+#else
     using return_type = typename std::result_of<F(Args...)>::type;
+#endif
 
     auto task = std::make_shared< std::packaged_task<return_type()> >(
             std::bind(std::forward<F>(f), std::forward<Args>(args)...)
diff --git a/src/sfizz/Opcode.cpp b/src/sfizz/Opcode.cpp
index 5468417e7..b983cba8b 100644
--- a/src/sfizz/Opcode.cpp
+++ b/src/sfizz/Opcode.cpp
@@ -6,6 +6,7 @@
 
 #include "Opcode.h"
 #include "LFODescription.h"
+#include "absl/strings/string_view.h"
 #include "utility/StringViewHelpers.h"
 #include "utility/Debug.h"
 #include <absl/strings/ascii.h>
@@ -271,11 +272,10 @@ absl::optional<uint8_t> readNoteValue(absl::string_view value)
     ///
     std::pair<absl::string_view, int> flatSharpPrefixes[] = {
         {   "#", +1 },
-        { u8"♯", +1 },
+        { (const char*)u8"♯", +1 },
         {   "b", -1 },
-        { u8"♭", -1 },
+        { (const char*)u8"♭", -1 },
     };
-
     for (const auto& prefix : flatSharpPrefixes) {
         if (absl::StartsWith(value, prefix.first)) {
             if (prefix.second == +1) {
@@ -304,6 +304,13 @@ absl::optional<uint8_t> readNoteValue(absl::string_view value)
     return static_cast<uint8_t>(noteNumber);
 }
 
+#if defined(__cpp_lib_char8_t)
+absl::optional<uint8_t> readNoteValue(std::u8string_view value)
+{
+    return readNoteValue(absl::string_view { reinterpret_cast<const char*>(value.data()), value.size() });
+}
+#endif
+
 absl::optional<bool> readBoolean(absl::string_view value)
 {
     // Cakewalk-style booleans, case-insensitive
diff --git a/src/sfizz/Opcode.h b/src/sfizz/Opcode.h
index 16557c3f9..d2deea670 100644
--- a/src/sfizz/Opcode.h
+++ b/src/sfizz/Opcode.h
@@ -143,6 +143,16 @@ struct Opcode {
  */
 absl::optional<uint8_t> readNoteValue(absl::string_view value);
 
+#if defined(__cpp_lib_char8_t)
+/**
+ * @brief Convert a note in string to its equivalent midi note number
+ *
+ * @param value
+ * @return absl::optional<uint8_t>
+ */
+absl::optional<uint8_t> readNoteValue(std::u8string_view value);
+#endif
+
 /**
  * @brief Read a boolean value from the sfz file and cast it to the destination parameter.
  */
diff --git a/src/sfizz/Synth.cpp b/src/sfizz/Synth.cpp
index a06777a7f..c5e2bb3a6 100644
--- a/src/sfizz/Synth.cpp
+++ b/src/sfizz/Synth.cpp
@@ -8,6 +8,7 @@
 #include "Config.h"
 #include "utility/Debug.h"
 #include "utility/Macros.h"
+#include "utility/U8Strings.h"
 #include "modulations/ModId.h"
 #include "modulations/ModKey.h"
 #include "modulations/ModMatrix.h"
@@ -702,7 +703,7 @@ void Synth::Impl::finalizeSfzLoad()
     filePool.setRootDirectory(rootDirectory);
 
     // a string representation used for OSC purposes
-    rootPath_ = rootDirectory.u8string();
+    rootPath_ = u8EncodedString(rootDirectory);
 
     size_t currentRegionIndex = 0;
     size_t currentRegionCount = layers_.size();
diff --git a/src/sfizz/import/foreign_instruments/AudioFile.cpp b/src/sfizz/import/foreign_instruments/AudioFile.cpp
index 65457cb1f..d4c4d3045 100644
--- a/src/sfizz/import/foreign_instruments/AudioFile.cpp
+++ b/src/sfizz/import/foreign_instruments/AudioFile.cpp
@@ -5,6 +5,7 @@
 // If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
 
 #include "AudioFile.h"
+#include "utility/U8Strings.h"
 #include <absl/strings/match.h>
 #include <absl/strings/string_view.h>
 #include <absl/memory/memory.h>
@@ -31,8 +32,7 @@ const char* AudioFileInstrumentFormat::name() const noexcept
 
 bool AudioFileInstrumentFormat::matchesFilePath(const fs::path& path) const
 {
-    const std::string ext = path.extension().u8string();
-
+    const std::string ext = u8EncodedString(path.extension());
     for (absl::string_view knownExt : kRecognizedAudioExtensions) {
         if (absl::EqualsIgnoreCase(ext, knownExt))
             return true;
@@ -51,7 +51,7 @@ std::string AudioFileInstrumentImporter::convertToSfz(const fs::path& path) cons
 {
     std::ostringstream os;
     os.imbue(std::locale::classic());
-    os << "<region>sample=" << path.filename().u8string();
+    os << "<region>sample=" << u8EncodedString(path.filename());
     return os.str();
 }
 
diff --git a/src/sfizz/import/foreign_instruments/DecentSampler.cpp b/src/sfizz/import/foreign_instruments/DecentSampler.cpp
index 149ba86d1..492ea5e56 100644
--- a/src/sfizz/import/foreign_instruments/DecentSampler.cpp
+++ b/src/sfizz/import/foreign_instruments/DecentSampler.cpp
@@ -6,6 +6,7 @@
 
 #include "DecentSampler.h"
 #include "sfizz/Opcode.h"
+#include "utility/U8Strings.h"
 #include <absl/strings/match.h>
 #include <absl/strings/string_view.h>
 #include <absl/memory/memory.h>
@@ -29,7 +30,7 @@ const char* DecentSamplerInstrumentFormat::name() const noexcept
 
 bool DecentSamplerInstrumentFormat::matchesFilePath(const fs::path& path) const
 {
-    const std::string ext = path.extension().u8string();
+    const std::string ext = u8EncodedString(path.extension());
     return absl::EqualsIgnoreCase(ext, ".dspreset");
 }
 
diff --git a/src/sfizz/utility/Size.h b/src/sfizz/utility/Size.h
index f7d5277ca..86b593015 100644
--- a/src/sfizz/utility/Size.h
+++ b/src/sfizz/utility/Size.h
@@ -8,6 +8,7 @@
 
 #include <type_traits>
 
+#if !defined(__cpp_lib_ssize)
 template<class C>
 constexpr auto ssize(const C& c)
     -> std::common_type_t<std::ptrdiff_t,
@@ -23,3 +24,4 @@ constexpr std::ptrdiff_t ssize(const T (&)[N]) noexcept
 {
     return N;
 }
+#endif
diff --git a/src/sfizz/utility/U8Strings.h b/src/sfizz/utility/U8Strings.h
new file mode 100644
index 000000000..c3c3ab18c
--- /dev/null
+++ b/src/sfizz/utility/U8Strings.h
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#pragma once
+
+#include "ghc/fs_std.hpp"
+#include <string>
+
+inline std::string from_u8string(const std::string &s) {
+    return s;
+}
+
+inline std::string from_u8string(std::string &&s) {
+    return std::move(s);
+}
+
+#if defined(__cpp_lib_char8_t)
+inline std::string from_u8string(const std::u8string &s) {
+    return std::string(s.begin(), s.end());
+}
+#endif
+
+inline std::string u8EncodedString(const fs::path& path) {
+    return from_u8string(path.u8string());
+}