diff --git a/pmb/__init__.py b/pmb/__init__.py
index 88feb678..ceb13a12 100644
--- a/pmb/__init__.py
+++ b/pmb/__init__.py
@@ -38,6 +38,8 @@ def main():
             raise RuntimeError("Work path not found, please run 'pmbootstrap"
                                " init' to create it.")
 
+        other.check_old_devices(args)
+
         # Migrate work folder if necessary
         if args.action not in ["shutdown", "zap", "log"]:
             other.migrate_work_folder(args)
diff --git a/pmb/helpers/other.py b/pmb/helpers/other.py
index b2cb0038..f759701d 100644
--- a/pmb/helpers/other.py
+++ b/pmb/helpers/other.py
@@ -1,5 +1,6 @@
 # Copyright 2020 Oliver Smith
 # SPDX-License-Identifier: GPL-3.0-or-later
+import glob
 import logging
 import os
 import re
@@ -173,6 +174,22 @@ def migrate_work_folder(args):
                            " be lost.")
 
 
+def check_old_devices(args):
+    """
+    Check if there are any device ports in device/*/APKBUILD,
+    rather than device/*/*/APKBUILD (e.g. device/testing/...).
+    """
+
+    g = glob.glob(args.aports + "/device/*/APKBUILD")
+    if not g:
+        return
+
+    raise RuntimeError("Found device ports outside device/testing/... "
+                       "Please run 'pmbootstrap pull' and/or move the "
+                       "following device ports to device/testing:\n - " +
+                       '\n - '.join(g))
+
+
 def validate_hostname(hostname):
     """
     Check whether the string is a valid hostname, according to