diff --git a/rlpython/command_line.py b/rlpython/command_line.py
index cac1f4b..f72dab6 100644
--- a/rlpython/command_line.py
+++ b/rlpython/command_line.py
@@ -19,25 +19,6 @@ def handle_command_line():
 
     namespace = argument_parser.parse_args()
 
-    # frontend mode
-    if namespace.frontend_mode:
-        def restore_pgrp(*args, **kwargs):
-            os.tcsetpgrp(fd, old_pgrp)
-            os.setpgid(0, old_pgrp)
-
-            exit(0)
-
-        signal.signal(signal.SIGTSTP, signal.SIG_IGN)
-        signal.signal(signal.SIGTTOU, signal.SIG_IGN)
-        signal.signal(signal.SIGTERM, restore_pgrp)
-
-        pid = os.getpid()
-        fd = os.open('/dev/tty', os.O_RDONLY)
-        old_pgrp = os.tcgetpgrp(fd)
-
-        os.setpgid(0, pid)
-        os.tcsetpgrp(fd, pid)
-
     # client mode
     if namespace.url:
         try:
@@ -55,12 +36,6 @@ def restore_pgrp(*args, **kwargs):
         finally:
             repl_client.shutdown()
 
-            if namespace.frontend_mode:
-                restore_pgrp()
-
-        if namespace.frontend_mode:
-            restore_pgrp()
-
         exit(0)
 
     # local mode
@@ -76,17 +51,12 @@ def restore_pgrp(*args, **kwargs):
 
         repl_kwargs[key] = value
 
-    try:
-        embed(
-            globals={},
-            single_threaded=True,
-            started_from_cmd_line=True,
-            **repl_kwargs,
-        )
-
-    finally:
-        if namespace.frontend_mode:
-            restore_pgrp()
+    embed(
+        globals={},
+        single_threaded=True,
+        started_from_cmd_line=True,
+        **repl_kwargs,
+    )
 
 
 if __name__ == '__main__':
diff --git a/rlpython/embed.py b/rlpython/embed.py
index 1eb6e23..15271f7 100644
--- a/rlpython/embed.py
+++ b/rlpython/embed.py
@@ -1,9 +1,17 @@
+from threading import Lock
 import inspect
 import logging
 import os
 
+_lock = Lock()
 
-def embed(single_threaded=False, bind='', permissions='600',
+
+def embed(*args, **kwargs):
+    with _lock:
+        return _embed(*args, **kwargs)
+
+
+def _embed(single_threaded=False, bind='', permissions='600',
           multi_session=False, started_from_cmd_line=False, print=print,
           debug=False, **repl_kwargs):
 
@@ -19,7 +27,7 @@ def embed(single_threaded=False, bind='', permissions='600',
     # use namespace of caller instead of own if nothing is set
     if 'globals' not in repl_kwargs:
         stack = inspect.stack()
-        frame_info = stack[1]
+        frame_info = stack[2]
 
         repl_kwargs['globals'] = {
             **frame_info.frame.f_globals,
diff --git a/rlpython/frontend.py b/rlpython/frontend.py
index 3254747..139055d 100644
--- a/rlpython/frontend.py
+++ b/rlpython/frontend.py
@@ -1,14 +1,24 @@
-import subprocess
+from threading import Thread
 import sys
+import os
 
 
 def start_frontend(port):
-    process = subprocess.Popen([
-        sys.executable,
-        '-m',
-        'rlpython.command_line',
-        'localhost:{}'.format(port),
-        '--frontend',
-    ])
-
-    return process
+    def _run():
+        os.system(
+            '{} -m rlpython.command_line localhost:{} --frontend'.format(
+                sys.executable,
+                port,
+            ),
+        )
+
+    thread = Thread(
+        name='rlpython Frontend',
+        daemon=False,
+        target=_run,
+    )
+
+    thread.start()
+
+    return thread
+