diff --git a/pmb/helpers/other.py b/pmb/helpers/other.py
index e2d652158ca0a080c076699db63ce859074cfb9a..ec293feef364f98eb2528b15e6f189249cc2ed5e 100644
--- a/pmb/helpers/other.py
+++ b/pmb/helpers/other.py
@@ -24,6 +24,14 @@ import pmb.config
 import pmb.helpers.run
 
 
+def getpackagelist(aportsdir):
+    packages=set()
+    for dir in os.listdir(aportsdir):
+        for package in os.listdir('aports/'+dir):
+            packages.add(package)
+    return packages
+
+
 def folder_size(args, path):
     """
     Run `du` to calculate the size of a folder (this is less code and
diff --git a/pmb/parse/arguments.py b/pmb/parse/arguments.py
index 62be77acac13508a1f870f0fddfe5086f8cc2a06..c61d1f6ced6618103505eb70f38dcc00042408cb 100644
--- a/pmb/parse/arguments.py
+++ b/pmb/parse/arguments.py
@@ -430,7 +430,7 @@ def arguments():
                        " is incompatible with how Alpine's abuild handles it.",
                        dest="ignore_depends")
     for action in [checksum, build, aportgen]:
-        action.add_argument("packages", nargs="+")
+        action.add_argument("packages", nargs="+", metavar="PACKAGES", choices=pmb.helpers.other.getpackagelist("aports"))
 
     # Action: kconfig_check / apkbuild_parse
     kconfig_check = sub.add_parser("kconfig_check", help="check, whether all"