diff --git a/src/python/jw/pkg/lib/util.py b/src/python/jw/pkg/lib/util.py
index 9378c8a2..5cc92e4b 100644
--- a/src/python/jw/pkg/lib/util.py
+++ b/src/python/jw/pkg/lib/util.py
@@ -104,6 +104,15 @@ async def run_cmd(
             )
 
             def _spawn():
+                # Apply env in PTY mode by temporarily updating os.environ around spawn.
+                if env:
+                    old_env = os.environ.copy()
+                    try:
+                        os.environ.update(env)
+                        return pty.spawn(args, master_read=reader)
+                    finally:
+                        os.environ.clear()
+                        os.environ.update(old_env)
                 return pty.spawn(args, master_read=reader)
 
             __check_exit_code(await asyncio.to_thread(_spawn))