diff --git a/unix/README.md b/unix/README.md
index 27e2575d..03e79d71 100644
--- a/unix/README.md
+++ b/unix/README.md
@@ -63,6 +63,7 @@ wallet (on testnet, always with the same seed). But there are other options:
 - `--segregate` => scroll down to `Running simulators in parallel` section
 - `--bricked` => simulate a system w/ bricked SE1: no more pin tries, etc.
 - `--fails N` => simulate N wrong PIN attempts before login, where (1 <= N <= 13)
+- `--log` => enable logging to `/tmp/cc_simulator.log`, or to `/tmp/cc-simulators/<pid>/cc_simulator.log` when used with `--segregate`
 
 See `variant/sim_settings.py` for the details of settings-related options.
 
diff --git a/unix/simulator.py b/unix/simulator.py
index af7e94fa..624d1e1a 100755
--- a/unix/simulator.py
+++ b/unix/simulator.py
@@ -863,12 +863,15 @@ def sock_cleanup():
     cc_mpy = os.path.join(cwd, "coldcard-mpy")
     sim_boot = os.path.join(cwd, "sim_boot.py")
 
+    log_base_dir = "/tmp"
+
     if segregate:
         os.makedirs("/tmp/cc-simulators", exist_ok=True)
         os.chdir("/tmp/cc-simulators")
         # our new work /tmp/cc-simulators/<PID>
         os.mkdir(str(pid))
         os.chdir(str(pid))
+        log_base_dir = os.getcwd()
         os.mkdir("MicroSD")
         os.mkdir("settings")
         os.mkdir("VirtDisk")
@@ -903,8 +906,20 @@ def sock_cleanup():
         child.kill()
         return
 
-    xterm = subprocess.Popen(['xterm', '-title', 'Coldcard Simulator REPL',
-                                '-geom', '132x40+650+40', '-e'] + cc_cmd,
+    xterm_args = ['xterm', '-title', 'Coldcard Simulator REPL', '-geom', '132x40+650+40']
+
+    log = ("--log" in sys.argv)
+    if log:
+        logfile = os.path.join(log_base_dir, 'cc_simulator.log')
+        # create or truncate logfile and set correct permissions before starting xterm
+        file_desc = os.open(logfile, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o644)
+        os.close(file_desc)
+
+        xterm_args.extend(['-l', '-lf', logfile, '-e'])
+    else:
+        xterm_args.extend(['-e'])
+
+    xterm = subprocess.Popen(xterm_args + cc_cmd,
                                 env=env,
                                 stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
                                 pass_fds=pass_fds, shell=False)