diff --git a/nixos/lib/test-driver/test_driver/machine.py b/nixos/lib/test-driver/test_driver/machine.py
index 1c77550bd1fd..0db7930f496b 100644
--- a/nixos/lib/test-driver/test_driver/machine.py
+++ b/nixos/lib/test-driver/test_driver/machine.py
@@ -545,7 +545,7 @@ class Machine:
         self.shell.send("echo ${PIPESTATUS[0]}\n".encode())
         rc = int(self._next_newline_closed_block_from_shell().strip())
 
-        return (rc, output.decode())
+        return (rc, output.decode(errors="replace"))
 
     def shell_interact(self, address: Optional[str] = None) -> None:
         """Allows you to interact with the guest shell for debugging purposes.