diff --git a/sherpa-onnx/csrc/offline-recognizer-ctc-impl.h b/sherpa-onnx/csrc/offline-recognizer-ctc-impl.h
index 2f49613503..ca0b5522ec 100644
--- a/sherpa-onnx/csrc/offline-recognizer-ctc-impl.h
+++ b/sherpa-onnx/csrc/offline-recognizer-ctc-impl.h
@@ -45,8 +45,10 @@ static OfflineRecognitionResult Convert(const OfflineCtcDecoderResult &src,
     auto sym = sym_table[src.tokens[i]];
     text.append(sym);
 
-    if (sym.size() == 1 && sym[0] != ' ') {
+    if (sym.size() == 1 && (sym[0] < 0x20 || sym[0] > 0x7e)) {
       // for byte bpe models
+      // (but don't rewrite printable characters 0x20..0x7e,
+      //  which collide with standard BPE units)
       std::ostringstream os;
       os << "<0x" << std::hex << std::uppercase
          << (static_cast<int32_t>(sym[0]) & 0xff) << ">";
diff --git a/sherpa-onnx/csrc/offline-recognizer-transducer-impl.h b/sherpa-onnx/csrc/offline-recognizer-transducer-impl.h
index 084d39fe9f..de9f6263b0 100644
--- a/sherpa-onnx/csrc/offline-recognizer-transducer-impl.h
+++ b/sherpa-onnx/csrc/offline-recognizer-transducer-impl.h
@@ -46,8 +46,10 @@ static OfflineRecognitionResult Convert(
     auto sym = sym_table[i];
     text.append(sym);
 
-    if (sym.size() == 1 && sym[0] != ' ') {
-      // for byte bpe models
+    if (sym.size() == 1 && (sym[0] < 0x20 || sym[0] > 0x7e)) {
+      // for byte bpe models,
+      // (but don't rewrite printable characters 0x20..0x7e,
+      //  which collide with standard BPE units)
       std::ostringstream os;
       os << "<0x" << std::hex << std::uppercase
          << (static_cast<int32_t>(sym[0]) & 0xff) << ">";
diff --git a/sherpa-onnx/csrc/online-recognizer-ctc-impl.h b/sherpa-onnx/csrc/online-recognizer-ctc-impl.h
index fa81d6590c..5697a77e8a 100644
--- a/sherpa-onnx/csrc/online-recognizer-ctc-impl.h
+++ b/sherpa-onnx/csrc/online-recognizer-ctc-impl.h
@@ -38,8 +38,10 @@ static OnlineRecognizerResult Convert(const OnlineCtcDecoderResult &src,
 
     r.text.append(sym);
 
-    if (sym.size() == 1 && sym[0] != ' ') {
+    if (sym.size() == 1 && (sym[0] < 0x20 || sym[0] > 0x7e)) {
       // for byte bpe models
+      // (but don't rewrite printable characters 0x20..0x7e,
+      //  which collide with standard BPE units)
       std::ostringstream os;
       os << "<0x" << std::hex << std::uppercase
          << (static_cast<int32_t>(sym[0]) & 0xff) << ">";
diff --git a/sherpa-onnx/csrc/online-recognizer-transducer-impl.h b/sherpa-onnx/csrc/online-recognizer-transducer-impl.h
index 8b193a67ea..b3f31cdd0e 100644
--- a/sherpa-onnx/csrc/online-recognizer-transducer-impl.h
+++ b/sherpa-onnx/csrc/online-recognizer-transducer-impl.h
@@ -50,8 +50,10 @@ static OnlineRecognizerResult Convert(const OnlineTransducerDecoderResult &src,
 
     r.text.append(sym);
 
-    if (sym.size() == 1 && sym[0] != ' ') {
+    if (sym.size() == 1 && (sym[0] < 0x20 || sym[0] > 0x7e)) {
       // for byte bpe models
+      // (but don't rewrite printable characters 0x20..0x7e,
+      //  which collide with standard BPE units)
       std::ostringstream os;
       os << "<0x" << std::hex << std::uppercase
          << (static_cast<int32_t>(sym[0]) & 0xff) << ">";