diff --git a/src/sfizz/FileId.cpp b/src/sfizz/FileId.cpp
index 8355ab70..13dca994 100644
--- a/src/sfizz/FileId.cpp
+++ b/src/sfizz/FileId.cpp
@@ -10,15 +10,17 @@
 
 size_t std::hash<sfz::FileId>::operator()(const sfz::FileId &id) const
 {
-    uint64_t h = ::hash(id.filename);
-    h = ::hash(id.reverse ? "!" : "", h);
+    uint64_t h = ::hash(id.filename());
+    h = ::hash(id.isReverse() ? "!" : "", h);
     return h;
 }
 
 std::ostream &operator<<(std::ostream &os, const sfz::FileId &fileId)
 {
-    os << fileId.filename;
-    if (fileId.reverse)
+    os << fileId.filename();
+    if (fileId.isReverse())
         os << " (reverse)";
     return os;
 }
+
+const std::string sfz::FileId::emptyFilename;
diff --git a/src/sfizz/FileId.h b/src/sfizz/FileId.h
index 7193bdd0..df97f1fd 100644
--- a/src/sfizz/FileId.h
+++ b/src/sfizz/FileId.h
@@ -6,6 +6,7 @@
 
 #pragma once
 #include <string>
+#include <memory>
 #include <iosfwd>
 
 namespace sfz {
@@ -14,9 +15,6 @@ namespace sfz {
  * @brief Sample file identifier within a file pool.
  */
 struct FileId {
-    std::string filename;
-    bool reverse = false;
-
     /**
      * @brief Construct a null identifier.
      */
@@ -30,11 +28,46 @@ struct FileId {
      * @param filename
      * @param reverse
      */
-    FileId(std::string filename, bool reverse = false)
-        : filename(std::move(filename)), reverse(reverse)
+    explicit FileId(std::string filename, bool reverse = false)
+        : filenameBuffer(new std::string(std::move(filename))),
+          reverse(reverse)
     {
     }
 
+    /**
+     * @brief Make an identifier which is a clone of the callee, except with the
+     * reverse flag passed as parameter.
+     *
+     * @param reverse
+     */
+    FileId reversed(bool reverse = true)
+    {
+        FileId id;
+        id.filenameBuffer = filenameBuffer;
+        id.reverse = reverse;
+        return id;
+    }
+
+    /**
+     * @brief Get the file name of this identifier.
+     *
+     * @return file name
+     */
+    const std::string &filename() const noexcept
+    {
+        return filenameBuffer ? *filenameBuffer : emptyFilename;
+    }
+
+    /**
+     * @brief Get whether the identified file is reversed.
+     *
+     * @return bool
+     */
+    bool isReverse() const noexcept
+    {
+        return reverse;
+    }
+
     /**
      * @brief Check equality with another identifier.
      *
@@ -42,7 +75,7 @@ struct FileId {
      */
     bool operator==(const FileId &other) const
     {
-        return reverse == other.reverse && filename == other.filename;
+        return reverse == other.reverse && filename() == other.filename();
     }
 
     /**
@@ -54,6 +87,11 @@ struct FileId {
     {
         return !operator==(other);
     }
+
+private:
+    std::shared_ptr<std::string> filenameBuffer;
+    bool reverse = false;
+    static const std::string emptyFilename;
 };
 
 }
diff --git a/src/sfizz/FilePool.cpp b/src/sfizz/FilePool.cpp
index f9f38ae7..b8e9ade4 100644
--- a/src/sfizz/FilePool.cpp
+++ b/src/sfizz/FilePool.cpp
@@ -190,9 +190,18 @@ bool sfz::FilePool::checkSample(std::string& filename) const noexcept
 #endif
 }
 
+bool sfz::FilePool::checkSampleId(FileId& fileId) const noexcept
+{
+    std::string filename = fileId.filename();
+    bool result = checkSample(filename);
+    if (result)
+        fileId = FileId(std::move(filename), fileId.isReverse());
+    return result;
+}
+
 absl::optional<sfz::FileInformation> sfz::FilePool::getFileInformation(const FileId& fileId) noexcept
 {
-    const fs::path file { rootDirectory / fileId.filename };
+    const fs::path file { rootDirectory / fileId.filename() };
 
     if (!fs::exists(file))
         return {};
@@ -208,7 +217,7 @@ absl::optional<sfz::FileInformation> sfz::FilePool::getFileInformation(const Fil
     returnedValue.sampleRate = static_cast<double>(sndFile.samplerate());
     returnedValue.numChannels = sndFile.channels();
 
-    if (!fileId.reverse) {
+    if (!fileId.isReverse()) {
         SF_INSTRUMENT instrumentInfo;
         sndFile.command(SFC_GET_INSTRUMENT, &instrumentInfo, sizeof(instrumentInfo));
         if (instrumentInfo.loop_count > 0) {
@@ -229,7 +238,7 @@ bool sfz::FilePool::preloadFile(const FileId& fileId, uint32_t maxOffset) noexce
     if (!fileInformation)
         return false;
 
-    const fs::path file { rootDirectory / fileId.filename };
+    const fs::path file { rootDirectory / fileId.filename() };
     SndfileHandle sndFile(file.string().c_str());
 
     // FIXME: Large offsets will require large preloading; is this OK in practice? Apparently sforzando does the same
@@ -244,12 +253,12 @@ bool sfz::FilePool::preloadFile(const FileId& fileId, uint32_t maxOffset) noexce
     const auto existingFile = preloadedFiles.find(fileId);
     if (existingFile != preloadedFiles.end()) {
         if (framesToLoad > existingFile->second.preloadedData->getNumFrames()) {
-            preloadedFiles[fileId].preloadedData = readFromFile<float>(sndFile, framesToLoad, oversamplingFactor, fileId.reverse);
+            preloadedFiles[fileId].preloadedData = readFromFile<float>(sndFile, framesToLoad, oversamplingFactor, fileId.isReverse());
         }
     } else {
         fileInformation->sampleRate = static_cast<float>(oversamplingFactor) * static_cast<float>(sndFile.samplerate());
         FileDataHandle handle {
-            readFromFile<float>(sndFile, framesToLoad, oversamplingFactor, fileId.reverse),
+            readFromFile<float>(sndFile, framesToLoad, oversamplingFactor, fileId.isReverse()),
             *fileInformation
         };
         preloadedFiles.insert_or_assign(fileId, handle);
@@ -263,7 +272,7 @@ absl::optional<sfz::FileDataHandle> sfz::FilePool::loadFile(const FileId& fileId
     if (!fileInformation)
         return {};
 
-    const fs::path file { rootDirectory / fileId.filename };
+    const fs::path file { rootDirectory / fileId.filename() };
     SndfileHandle sndFile(file.string().c_str());
 
     // FIXME: Large offsets will require large preloading; is this OK in practice? Apparently sforzando does the same
@@ -274,7 +283,7 @@ absl::optional<sfz::FileDataHandle> sfz::FilePool::loadFile(const FileId& fileId
     } else {
         fileInformation->sampleRate = static_cast<float>(oversamplingFactor) * static_cast<float>(sndFile.samplerate());
         FileDataHandle handle {
-            readFromFile<float>(sndFile, frames, oversamplingFactor, fileId.reverse),
+            readFromFile<float>(sndFile, frames, oversamplingFactor, fileId.isReverse()),
             *fileInformation
         };
         loadedFiles.insert_or_assign(fileId, handle);
@@ -322,9 +331,9 @@ void sfz::FilePool::setPreloadSize(uint32_t preloadSize) noexcept
     for (auto& preloadedFile : preloadedFiles) {
         const auto numFrames = preloadedFile.second.preloadedData->getNumFrames() / static_cast<int>(oversamplingFactor);
         const auto maxOffset = numFrames > this->preloadSize ? static_cast<uint32_t>(numFrames) - this->preloadSize : 0;
-        fs::path file { rootDirectory / preloadedFile.first.filename };
+        fs::path file { rootDirectory / preloadedFile.first.filename() };
         SndfileHandle sndFile(file.string().c_str());
-        preloadedFile.second.preloadedData = readFromFile<float>(sndFile, preloadSize + maxOffset, oversamplingFactor, preloadedFile.first.reverse);
+        preloadedFile.second.preloadedData = readFromFile<float>(sndFile, preloadSize + maxOffset, oversamplingFactor, preloadedFile.first.isReverse());
     }
     this->preloadSize = preloadSize;
 }
@@ -372,7 +381,7 @@ void sfz::FilePool::loadingThread() noexcept
         const auto loadStartTime = std::chrono::high_resolution_clock::now();
         const auto waitDuration = loadStartTime - promise->creationTime;
 
-        const fs::path file { rootDirectory / promise->fileId.filename };
+        const fs::path file { rootDirectory / promise->fileId.filename() };
         SndfileHandle sndFile(file.string().c_str());
         if (sndFile.error() != 0) {
             DBG("[sfizz] libsndfile errored for " << promise->fileId << " with message " << sndFile.strError());
@@ -380,10 +389,10 @@ void sfz::FilePool::loadingThread() noexcept
             continue;
         }
         const auto frames = static_cast<uint32_t>(sndFile.frames());
-        streamFromFile<float>(sndFile, frames, oversamplingFactor, promise->fileId.reverse, promise->fileData, &promise->availableFrames);
+        streamFromFile<float>(sndFile, frames, oversamplingFactor, promise->fileId.isReverse(), promise->fileData, &promise->availableFrames);
         promise->dataStatus = FilePromise::DataStatus::Ready;
         const auto loadDuration = std::chrono::high_resolution_clock::now() - loadStartTime;
-        logger.logFileTime(waitDuration, loadDuration, frames, promise->fileId.filename);
+        logger.logFileTime(waitDuration, loadDuration, frames, promise->fileId.filename());
 
         threadsLoading--;
 
@@ -451,9 +460,9 @@ void sfz::FilePool::setOversamplingFactor(sfz::Oversampling factor) noexcept
     for (auto& preloadedFile : preloadedFiles) {
         const auto numFrames = preloadedFile.second.preloadedData->getNumFrames() / static_cast<int>(this->oversamplingFactor);
         const uint32_t maxOffset = numFrames > this->preloadSize ? static_cast<uint32_t>(numFrames) - this->preloadSize : 0;
-        fs::path file { rootDirectory / preloadedFile.first.filename };
+        fs::path file { rootDirectory / preloadedFile.first.filename() };
         SndfileHandle sndFile(file.string().c_str());
-        preloadedFile.second.preloadedData = readFromFile<float>(sndFile, preloadSize + maxOffset, factor, preloadedFile.first.reverse);
+        preloadedFile.second.preloadedData = readFromFile<float>(sndFile, preloadSize + maxOffset, factor, preloadedFile.first.isReverse());
         preloadedFile.second.information.sampleRate *= samplerateChange;
     }
 
diff --git a/src/sfizz/FilePool.h b/src/sfizz/FilePool.h
index 631dd6f6..7f5e15d9 100644
--- a/src/sfizz/FilePool.h
+++ b/src/sfizz/FilePool.h
@@ -189,6 +189,15 @@ public:
      */
     bool checkSample(std::string& filename) const noexcept;
 
+    /**
+     * @brief Check that the sample exists. If not, try to find it in a case insensitive way.
+     *
+     * @param fileId the sample file identifier; may be updated by the method
+     * @return true if the sample exists or was updated properly
+     * @return false if no sample was found even with a case insensitive search
+     */
+    bool checkSampleId(FileId& fileId) const noexcept;
+
     /**
      * @brief Clear all preloaded files.
      *
diff --git a/src/sfizz/Region.cpp b/src/sfizz/Region.cpp
index 0c6d954c..117a6d26 100644
--- a/src/sfizz/Region.cpp
+++ b/src/sfizz/Region.cpp
@@ -41,14 +41,17 @@ bool sfz::Region::parseOpcode(const Opcode& opcode)
             if (trimmedSample.empty())
                 break;
 
+            std::string filename;
             if (trimmedSample[0] == '*')
-                sampleId.filename = std::string(trimmedSample);
+                filename = std::string(trimmedSample);
             else
-                sampleId.filename = absl::StrCat(defaultPath, absl::StrReplaceAll(trimmedSample, { { "\\", "/" } }));
+                filename = absl::StrCat(defaultPath, absl::StrReplaceAll(trimmedSample, { { "\\", "/" } }));
+
+            sampleId = FileId(std::move(filename), sampleId.isReverse());
         }
         break;
     case hash("direction"):
-        sampleId.reverse = opcode.value == "reverse";
+        sampleId = sampleId.reversed(opcode.value == "reverse");
         break;
     case hash("delay"):
         setValueFromOpcode(opcode, delay, Default::delayRange);
diff --git a/src/sfizz/Region.h b/src/sfizz/Region.h
index 0ab2dd82..17180bca 100644
--- a/src/sfizz/Region.h
+++ b/src/sfizz/Region.h
@@ -58,7 +58,7 @@ struct Region {
      * @return true
      * @return false
      */
-    bool isGenerator() const noexcept { return sampleId.filename.size() > 0 ? sampleId.filename[0] == '*' : false; }
+    bool isGenerator() const noexcept { return sampleId.filename().size() > 0 ? sampleId.filename()[0] == '*' : false; }
     /**
      * @brief Is stereo (has stereo sample or is unison oscillator)?
      *
diff --git a/src/sfizz/Synth.cpp b/src/sfizz/Synth.cpp
index 2783718c..d16fc87e 100644
--- a/src/sfizz/Synth.cpp
+++ b/src/sfizz/Synth.cpp
@@ -350,7 +350,7 @@ bool sfz::Synth::loadSfzFile(const fs::path& file)
         auto region = currentRegion->get();
 
         if (!region->oscillator && !region->isGenerator()) {
-            if (!resources.filePool.checkSample(region->sampleId.filename)) {
+            if (!resources.filePool.checkSampleId(region->sampleId)) {
                 removeCurrentRegion();
                 continue;
             }
@@ -391,12 +391,12 @@ bool sfz::Synth::loadSfzFile(const fs::path& file)
                 removeCurrentRegion();
         }
         else if (region->oscillator && !region->isGenerator()) {
-            if (!resources.filePool.checkSample(region->sampleId.filename)) {
+            if (!resources.filePool.checkSampleId(region->sampleId)) {
                 removeCurrentRegion();
                 continue;
             }
 
-            if (!resources.wavePool.createFileWave(resources.filePool, region->sampleId.filename)) {
+            if (!resources.wavePool.createFileWave(resources.filePool, std::string(region->sampleId.filename()))) {
                 removeCurrentRegion();
                 continue;
             }
diff --git a/src/sfizz/Voice.cpp b/src/sfizz/Voice.cpp
index 68650ef0..7eea837a 100644
--- a/src/sfizz/Voice.cpp
+++ b/src/sfizz/Voice.cpp
@@ -40,7 +40,7 @@ void sfz::Voice::startVoice(Region* region, int delay, int number, float value,
 
     if (region->isGenerator()) {
         const WavetableMulti* wave = nullptr;
-        switch (hash(region->sampleId.filename)) {
+        switch (hash(region->sampleId.filename())) {
         default:
         case hash("*silence"):
             break;
@@ -64,7 +64,7 @@ void sfz::Voice::startVoice(Region* region, int delay, int number, float value,
         }
         setupOscillatorUnison();
     } else if (region->oscillator) {
-        const WavetableMulti* wave = resources.wavePool.getFileWave(region->sampleId.filename);
+        const WavetableMulti* wave = resources.wavePool.getFileWave(region->sampleId.filename());
         for (WavetableOscillator& osc : waveOscillators) {
             osc.setWavetable(wave);
             osc.setPhase(region->getPhase());
@@ -529,7 +529,7 @@ void sfz::Voice::fillWithGenerator(AudioSpan<float> buffer) noexcept
     const auto leftSpan = buffer.getSpan(0);
     const auto rightSpan  = buffer.getSpan(1);
 
-    if (region->sampleId.filename == "*noise") {
+    if (region->sampleId.filename() == "*noise") {
         absl::c_generate(leftSpan, [&](){ return noiseDist(Random::randomGenerator); });
         absl::c_generate(rightSpan, [&](){ return noiseDist(Random::randomGenerator); });
     } else {
diff --git a/src/sfizz/Wavetables.cpp b/src/sfizz/Wavetables.cpp
index 617d3901..c1a4448b 100644
--- a/src/sfizz/Wavetables.cpp
+++ b/src/sfizz/Wavetables.cpp
@@ -365,7 +365,7 @@ bool WavetablePool::createFileWave(FilePool& filePool, const std::string& filena
     if (_fileWaves.contains(filename))
         return true;
 
-    auto fileHandle = filePool.loadFile(filename);
+    auto fileHandle = filePool.loadFile(FileId(filename));
     if (!fileHandle)
         return false;
 
diff --git a/tests/FilesT.cpp b/tests/FilesT.cpp
index e6c2394e..2f22dea5 100644
--- a/tests/FilesT.cpp
+++ b/tests/FilesT.cpp
@@ -19,7 +19,7 @@ TEST_CASE("[Files] Single region (regions_one.sfz)")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Regions/regions_one.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy.wav");
 }
 
 
@@ -28,9 +28,9 @@ TEST_CASE("[Files] Multiple regions (regions_many.sfz)")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Regions/regions_many.sfz");
     REQUIRE(synth.getNumRegions() == 3);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy.wav");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "dummy.1.wav");
-    REQUIRE(synth.getRegionView(2)->sampleId.filename == "dummy.2.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "dummy.1.wav");
+    REQUIRE(synth.getRegionView(2)->sampleId.filename() == "dummy.2.wav");
 }
 
 TEST_CASE("[Files] Basic opcodes (regions_opcodes.sfz)")
@@ -54,8 +54,8 @@ TEST_CASE("[Files] (regions_bad.sfz)")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Regions/regions_bad.sfz");
     REQUIRE(synth.getNumRegions() == 2);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy.wav");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "dummy.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "dummy.wav");
 }
 
 TEST_CASE("[Files] Local include")
@@ -63,7 +63,7 @@ TEST_CASE("[Files] Local include")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/root_local.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy.wav");
 }
 
 TEST_CASE("[Files] Multiple includes")
@@ -71,8 +71,8 @@ TEST_CASE("[Files] Multiple includes")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/multiple_includes.sfz");
     REQUIRE(synth.getNumRegions() == 2);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy.wav");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "dummy2.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "dummy2.wav");
 }
 
 TEST_CASE("[Files] Multiple includes with comments")
@@ -80,8 +80,8 @@ TEST_CASE("[Files] Multiple includes with comments")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/multiple_includes_with_comments.sfz");
     REQUIRE(synth.getNumRegions() == 2);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy.wav");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "dummy2.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "dummy2.wav");
 }
 
 TEST_CASE("[Files] Subdir include")
@@ -89,7 +89,7 @@ TEST_CASE("[Files] Subdir include")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/root_subdir.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy_subdir.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy_subdir.wav");
 }
 
 TEST_CASE("[Files] Subdir include Win")
@@ -97,7 +97,7 @@ TEST_CASE("[Files] Subdir include Win")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/root_subdir_win.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy_subdir.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy_subdir.wav");
 }
 
 TEST_CASE("[Files] Recursive include (with include guard)")
@@ -107,8 +107,8 @@ TEST_CASE("[Files] Recursive include (with include guard)")
     parser.setRecursiveIncludeGuardEnabled(true);
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/root_recursive.sfz");
     REQUIRE(synth.getNumRegions() == 2);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy_recursive2.wav");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "dummy_recursive1.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy_recursive2.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "dummy_recursive1.wav");
 }
 
 TEST_CASE("[Files] Include loops (with include guard)")
@@ -118,8 +118,8 @@ TEST_CASE("[Files] Include loops (with include guard)")
     parser.setRecursiveIncludeGuardEnabled(true);
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/Includes/root_loop.sfz");
     REQUIRE(synth.getNumRegions() == 2);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy_loop2.wav");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "dummy_loop1.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy_loop2.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "dummy_loop1.wav");
 }
 
 TEST_CASE("[Files] Define test")
@@ -205,28 +205,28 @@ TEST_CASE("[Files] Full hierarchy with antislashes")
         sfz::Synth synth;
         synth.loadSfzFile(fs::current_path() / "tests/TestFiles/basic_hierarchy.sfz");
         REQUIRE(synth.getNumRegions() == 8);
-        REQUIRE(synth.getRegionView(0)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(1)->sampleId.filename == "Regions/dummy.1.wav");
-        REQUIRE(synth.getRegionView(2)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(3)->sampleId.filename == "Regions/dummy.1.wav");
-        REQUIRE(synth.getRegionView(4)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(5)->sampleId.filename == "Regions/dummy.1.wav");
-        REQUIRE(synth.getRegionView(6)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(7)->sampleId.filename == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(0)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(1)->sampleId.filename() == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(2)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(3)->sampleId.filename() == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(4)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(5)->sampleId.filename() == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(6)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(7)->sampleId.filename() == "Regions/dummy.1.wav");
     }
 
     {
         sfz::Synth synth;
         synth.loadSfzFile(fs::current_path() / "tests/TestFiles/basic_hierarchy_antislash.sfz");
         REQUIRE(synth.getNumRegions() == 8);
-        REQUIRE(synth.getRegionView(0)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(1)->sampleId.filename == "Regions/dummy.1.wav");
-        REQUIRE(synth.getRegionView(2)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(3)->sampleId.filename == "Regions/dummy.1.wav");
-        REQUIRE(synth.getRegionView(4)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(5)->sampleId.filename == "Regions/dummy.1.wav");
-        REQUIRE(synth.getRegionView(6)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(7)->sampleId.filename == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(0)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(1)->sampleId.filename() == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(2)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(3)->sampleId.filename() == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(4)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(5)->sampleId.filename() == "Regions/dummy.1.wav");
+        REQUIRE(synth.getRegionView(6)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(7)->sampleId.filename() == "Regions/dummy.1.wav");
     }
 }
 
@@ -245,10 +245,10 @@ TEST_CASE("[Files] Pizz basic")
     REQUIRE(synth.getRegionView(1)->randRange == sfz::Range<float>(0.25, 0.5));
     REQUIRE(synth.getRegionView(2)->randRange == sfz::Range<float>(0.5, 0.75));
     REQUIRE(synth.getRegionView(3)->randRange == sfz::Range<float>(0.75, 1.0));
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == R"(../Samples/pizz/a0_vl4_rr1.wav)");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == R"(../Samples/pizz/a0_vl4_rr2.wav)");
-    REQUIRE(synth.getRegionView(2)->sampleId.filename == R"(../Samples/pizz/a0_vl4_rr3.wav)");
-    REQUIRE(synth.getRegionView(3)->sampleId.filename == R"(../Samples/pizz/a0_vl4_rr4.wav)");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == R"(../Samples/pizz/a0_vl4_rr1.wav)");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == R"(../Samples/pizz/a0_vl4_rr2.wav)");
+    REQUIRE(synth.getRegionView(2)->sampleId.filename() == R"(../Samples/pizz/a0_vl4_rr3.wav)");
+    REQUIRE(synth.getRegionView(3)->sampleId.filename() == R"(../Samples/pizz/a0_vl4_rr4.wav)");
 }
 
 TEST_CASE("[Files] Channels (channels.sfz)")
@@ -256,9 +256,9 @@ TEST_CASE("[Files] Channels (channels.sfz)")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/channels.sfz");
     REQUIRE(synth.getNumRegions() == 2);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "mono_sample.wav");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "mono_sample.wav");
     REQUIRE(!synth.getRegionView(0)->isStereo());
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "stereo_sample.wav");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "stereo_sample.wav");
     REQUIRE(synth.getRegionView(1)->isStereo());
 }
 
@@ -268,32 +268,32 @@ TEST_CASE("[Files] Channels (channels_multi.sfz)")
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/channels_multi.sfz");
     REQUIRE(synth.getNumRegions() == 6);
 
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == "*sine");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == "*sine");
     REQUIRE(!synth.getRegionView(0)->isStereo());
     REQUIRE(synth.getRegionView(0)->isGenerator());
     REQUIRE(!synth.getRegionView(0)->oscillator);
 
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == "*sine");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == "*sine");
     REQUIRE(synth.getRegionView(1)->isStereo());
     REQUIRE(synth.getRegionView(1)->isGenerator());
     REQUIRE(!synth.getRegionView(1)->oscillator);
 
-    REQUIRE(synth.getRegionView(2)->sampleId.filename == "ramp_wave.wav");
+    REQUIRE(synth.getRegionView(2)->sampleId.filename() == "ramp_wave.wav");
     REQUIRE(!synth.getRegionView(2)->isStereo());
     REQUIRE(!synth.getRegionView(2)->isGenerator());
     REQUIRE(synth.getRegionView(2)->oscillator);
 
-    REQUIRE(synth.getRegionView(3)->sampleId.filename == "ramp_wave.wav");
+    REQUIRE(synth.getRegionView(3)->sampleId.filename() == "ramp_wave.wav");
     REQUIRE(synth.getRegionView(3)->isStereo());
     REQUIRE(!synth.getRegionView(3)->isGenerator());
     REQUIRE(synth.getRegionView(3)->oscillator);
 
-    REQUIRE(synth.getRegionView(4)->sampleId.filename == "*sine");
+    REQUIRE(synth.getRegionView(4)->sampleId.filename() == "*sine");
     REQUIRE(!synth.getRegionView(4)->isStereo());
     REQUIRE(synth.getRegionView(4)->isGenerator());
     REQUIRE(!synth.getRegionView(4)->oscillator);
 
-    REQUIRE(synth.getRegionView(5)->sampleId.filename == "*sine");
+    REQUIRE(synth.getRegionView(5)->sampleId.filename() == "*sine");
     REQUIRE(!synth.getRegionView(5)->isStereo());
     REQUIRE(synth.getRegionView(5)->isGenerator());
     REQUIRE(!synth.getRegionView(5)->oscillator);
@@ -359,7 +359,7 @@ TEST_CASE("[Files] Specific bug: relative path with backslashes")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/SpecificBugs/win_backslashes.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == R"(Xylo/Subfolder/closedhat.wav)");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == R"(Xylo/Subfolder/closedhat.wav)");
 }
 
 TEST_CASE("[Files] Default path")
@@ -367,10 +367,10 @@ TEST_CASE("[Files] Default path")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/default_path.sfz");
     REQUIRE(synth.getNumRegions() == 4);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == R"(DefaultPath/SubPath1/sample1.wav)");
-    REQUIRE(synth.getRegionView(1)->sampleId.filename == R"(DefaultPath/SubPath2/sample2.wav)");
-    REQUIRE(synth.getRegionView(2)->sampleId.filename == R"(DefaultPath/SubPath1/sample1.wav)");
-    REQUIRE(synth.getRegionView(3)->sampleId.filename == R"(DefaultPath/SubPath2/sample2.wav)");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == R"(DefaultPath/SubPath1/sample1.wav)");
+    REQUIRE(synth.getRegionView(1)->sampleId.filename() == R"(DefaultPath/SubPath2/sample2.wav)");
+    REQUIRE(synth.getRegionView(2)->sampleId.filename() == R"(DefaultPath/SubPath1/sample1.wav)");
+    REQUIRE(synth.getRegionView(3)->sampleId.filename() == R"(DefaultPath/SubPath2/sample2.wav)");
 }
 
 TEST_CASE("[Files] Default path reset when calling loadSfzFile again")
@@ -380,7 +380,7 @@ TEST_CASE("[Files] Default path reset when calling loadSfzFile again")
     REQUIRE(synth.getNumRegions() == 4);
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/default_path_reset.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == R"(DefaultPath/SubPath2/sample2.wav)");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == R"(DefaultPath/SubPath2/sample2.wav)");
 }
 
 TEST_CASE("[Files] Default path is ignored for generators")
@@ -388,7 +388,7 @@ TEST_CASE("[Files] Default path is ignored for generators")
     sfz::Synth synth;
     synth.loadSfzFile(fs::current_path() / "tests/TestFiles/default_path_generator.sfz");
     REQUIRE(synth.getNumRegions() == 1);
-    REQUIRE(synth.getRegionView(0)->sampleId.filename == R"(*sine)");
+    REQUIRE(synth.getRegionView(0)->sampleId.filename() == R"(*sine)");
 }
 
 TEST_CASE("[Files] Set CC applies properly")
@@ -547,10 +547,10 @@ TEST_CASE("[Files] Case sentitiveness")
         sfz::Synth synth;
         synth.loadSfzFile(sfzFilePath);
         REQUIRE(synth.getNumRegions() == 4);
-        REQUIRE(synth.getRegionView(0)->sampleId.filename == "dummy1.wav");
-        REQUIRE(synth.getRegionView(1)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(2)->sampleId.filename == "Regions/dummy.wav");
-        REQUIRE(synth.getRegionView(3)->sampleId.filename == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(0)->sampleId.filename() == "dummy1.wav");
+        REQUIRE(synth.getRegionView(1)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(2)->sampleId.filename() == "Regions/dummy.wav");
+        REQUIRE(synth.getRegionView(3)->sampleId.filename() == "Regions/dummy.wav");
     }
 }
 
diff --git a/tests/RegionT.cpp b/tests/RegionT.cpp
index 14176337..fa73bd51 100644
--- a/tests/RegionT.cpp
+++ b/tests/RegionT.cpp
@@ -18,18 +18,18 @@ TEST_CASE("[Region] Parsing opcodes")
 
     SECTION("sample")
     {
-        REQUIRE(region.sampleId.filename == "");
+        REQUIRE(region.sampleId.filename() == "");
         region.parseOpcode({ "sample", "dummy.wav" });
-        REQUIRE(region.sampleId.filename == "dummy.wav");
+        REQUIRE(region.sampleId.filename() == "dummy.wav");
     }
 
     SECTION("direction")
     {
-        REQUIRE(!region.sampleId.reverse);
+        REQUIRE(!region.sampleId.isReverse());
         region.parseOpcode({ "direction", "reverse" });
-        REQUIRE(region.sampleId.reverse);
+        REQUIRE(region.sampleId.isReverse());
         region.parseOpcode({ "direction", "forward" });
-        REQUIRE(!region.sampleId.reverse);
+        REQUIRE(!region.sampleId.isReverse());
     }
 
     SECTION("delay")