diff --git a/rfg_vna_viewer.py b/rfg_vna_viewer.py
index 9d32571..413db7b 100644
--- a/rfg_vna_viewer.py
+++ b/rfg_vna_viewer.py
@@ -41,10 +41,15 @@ DATA_PATH = "/tmp/ttyADC_data"
 # DataReader
 # ---------------------------------------------------------------------------
 class DataReader:
-    """Non-blocking raw reader for /tmp/ttyADC_data."""
+    """Non-blocking raw reader for /tmp/ttyADC_data (PTY-safe)."""
 
     def __init__(self, path=DATA_PATH):
+        import termios, tty
         self._fd = os.open(path, os.O_RDONLY | os.O_NOCTTY)
+        try:
+            tty.setraw(self._fd)  # disable line discipline processing
+        except termios.error:
+            pass  # not a TTY — fine, skip
         os.set_blocking(self._fd, False)
 
     def read_available(self):