diff --git a/sherpa-onnx/csrc/lexicon.cc b/sherpa-onnx/csrc/lexicon.cc
index 87203f4e1..7014348c3 100644
--- a/sherpa-onnx/csrc/lexicon.cc
+++ b/sherpa-onnx/csrc/lexicon.cc
@@ -76,7 +76,9 @@ static std::vector<int32_t> ConvertTokensToIds(
 }
 
 Lexicon::Lexicon(const std::string &lexicon, const std::string &tokens,
-                 const std::string &punctuations, const std::string &language) {
+                 const std::string &punctuations, const std::string &language,
+                 bool debug /*= false*/)
+    : debug_(debug) {
   InitLanguage(language);
   InitTokens(tokens);
   InitLexicon(lexicon);
@@ -102,6 +104,20 @@ std::vector<int64_t> Lexicon::ConvertTextToTokenIdsChinese(
     const std::string &text) const {
   std::vector<std::string> words = SplitUtf8(text);
 
+  if (debug_) {
+    fprintf(stderr, "Input text in string: %s\n", text.c_str());
+    fprintf(stderr, "Input text in bytes:");
+    for (uint8_t c : text) {
+      fprintf(stderr, " %02x", c);
+    }
+    fprintf(stderr, "\n");
+    fprintf(stderr, "After splitting to words:");
+    for (const auto &w : words) {
+      fprintf(stderr, " %s", w.c_str());
+    }
+    fprintf(stderr, "\n");
+  }
+
   std::vector<int64_t> ans;
 
   auto sil = token2id_.at("sil");
diff --git a/sherpa-onnx/csrc/lexicon.h b/sherpa-onnx/csrc/lexicon.h
index 35bace8f8..211eb607f 100644
--- a/sherpa-onnx/csrc/lexicon.h
+++ b/sherpa-onnx/csrc/lexicon.h
@@ -17,7 +17,8 @@ namespace sherpa_onnx {
 class Lexicon {
  public:
   Lexicon(const std::string &lexicon, const std::string &tokens,
-          const std::string &punctuations, const std::string &language);
+          const std::string &punctuations, const std::string &language,
+          bool debug = false);
 
   std::vector<int64_t> ConvertTextToTokenIds(const std::string &text) const;
 
@@ -45,6 +46,7 @@ class Lexicon {
   std::unordered_set<std::string> punctuations_;
   std::unordered_map<std::string, int32_t> token2id_;
   Language language_;
+  bool debug_;
   //
 };
 
diff --git a/sherpa-onnx/csrc/offline-tts-vits-impl.h b/sherpa-onnx/csrc/offline-tts-vits-impl.h
index af1a001eb..6b19024e0 100644
--- a/sherpa-onnx/csrc/offline-tts-vits-impl.h
+++ b/sherpa-onnx/csrc/offline-tts-vits-impl.h
@@ -21,7 +21,8 @@ class OfflineTtsVitsImpl : public OfflineTtsImpl {
   explicit OfflineTtsVitsImpl(const OfflineTtsConfig &config)
       : model_(std::make_unique<OfflineTtsVitsModel>(config.model)),
         lexicon_(config.model.vits.lexicon, config.model.vits.tokens,
-                 model_->Punctuations(), model_->Language()) {}
+                 model_->Punctuations(), model_->Language(),
+                 config.model.debug) {}
 
   GeneratedAudio Generate(const std::string &text,
                           int64_t sid = 0) const override {