diff --git a/src/cpp/main.cpp b/src/cpp/main.cpp
index 8accd98..3204b2f 100644
--- a/src/cpp/main.cpp
+++ b/src/cpp/main.cpp
@@ -188,7 +188,7 @@ void parseArgs(int argc, char *argv[], RunConfig &runConfig) {
       runConfig.outputPath = filesystem::path(argv[++i]);
     } else if (arg == "-s" || arg == "--speaker") {
       ensureArg(argc, argv, i);
-      runConfig.speakerId = (larynx::SpeakerId)stoll(argv[++i]);
+      runConfig.speakerId = (larynx::SpeakerId)stoi(argv[++i]);
     } else if (arg == "-h" || arg == "--help") {
       printUsage(argv);
       exit(0);
diff --git a/src/cpp/synthesize.hpp b/src/cpp/synthesize.hpp
index a028549..ad8cdf3 100644
--- a/src/cpp/synthesize.hpp
+++ b/src/cpp/synthesize.hpp
@@ -53,10 +53,12 @@ void synthesize(SynthesisConfig &synthesisConfig, ModelSession &session,
       Ort::Value::CreateTensor<float>(memoryInfo, scales.data(), scales.size(),
                                       scalesShape.data(), scalesShape.size()));
 
+  // Add speaker id.
+  // NOTE: These must be kept outside the "if" below to avoid being deallocated.
+  vector<int64_t> speakerId{(int64_t)synthesisConfig.speakerId.value_or(0)};
+  vector<int64_t> speakerIdShape{(int64_t)speakerId.size()};
+
   if (synthesisConfig.speakerId) {
-    // Add speaker id
-    vector<int64_t> speakerId{(int64_t)synthesisConfig.speakerId.value()};
-    vector<int64_t> speakerIdShape{(int64_t)speakerId.size()};
     inputTensors.push_back(Ort::Value::CreateTensor<int64_t>(
         memoryInfo, speakerId.data(), speakerId.size(), speakerIdShape.data(),
         speakerIdShape.size()));
diff --git a/src/cpp/wavfile.hpp b/src/cpp/wavfile.hpp
index 06d6d76..6709217 100644
--- a/src/cpp/wavfile.hpp
+++ b/src/cpp/wavfile.hpp
@@ -27,7 +27,7 @@ struct WavHeader {
 
 // Write WAV file header only
 void writeWavHeader(int sampleRate, int sampleWidth, int channels,
-                    uint32_t numSamples, ostream &audioFile) {
+                    uint32_t numSamples, std::ostream &audioFile) {
   WavHeader header;
   header.chunkSize = numSamples + sizeof(WavHeader) - 8;
   header.sampleRate = sampleRate;