diff --git a/libagent/device/trezor.py b/libagent/device/trezor.py
index 95bf951..50ace4a 100644
--- a/libagent/device/trezor.py
+++ b/libagent/device/trezor.py
@@ -35,7 +35,7 @@ class Trezor(interface.Device):
             return self._defs.PassphraseAck(passphrase=self.passphrase)
 
         def create_pin_handler(conn):
-            if os.isatty(sys.stdin.fileno()):
+            if not sys.stdin.closed and os.isatty(sys.stdin.fileno()):
                 return conn.callback_PinMatrixRequest  # CLI-based PIN handler
 
             def qt_handler(_):
diff --git a/libagent/ssh/__init__.py b/libagent/ssh/__init__.py
index 5772d4d..75cf03c 100644
--- a/libagent/ssh/__init__.py
+++ b/libagent/ssh/__init__.py
@@ -210,6 +210,7 @@ def main(device_type):
     use_shell = bool(args.shell)
     if use_shell:
         command = os.environ['SHELL']
+        sys.stdin.close()
 
     conn = JustInTimeConnection(
         conn_factory=lambda: client.Client(device_type()),