diff --git a/pmb/aportgen/__init__.py b/pmb/aportgen/__init__.py
index e8b0dcec..9c614290 100644
--- a/pmb/aportgen/__init__.py
+++ b/pmb/aportgen/__init__.py
@@ -35,7 +35,7 @@ def get_cross_package_arches(pkgname: str) -> str:
         return "x86_64"
 
 
-def properties(pkgname):
+def properties(pkgname: str) -> tuple[str, str, AportGenEntry]:
     """
     Get the `pmb.config.aportgen` properties for the aport generator, based on
     the pkgname prefix.
diff --git a/pmb/aportgen/device.py b/pmb/aportgen/device.py
index 950db3db..e72bbc1f 100644
--- a/pmb/aportgen/device.py
+++ b/pmb/aportgen/device.py
@@ -13,7 +13,7 @@ import pmb.parse.apkindex
 import pmb.parse
 
 
-def ask_for_architecture():
+def ask_for_architecture() -> Arch:
     architectures = [str(a) for a in Arch.supported()]
     # Don't show armhf, new ports shouldn't use this architecture
     if "armhf" in architectures:
@@ -32,12 +32,12 @@ def ask_for_architecture():
         )
 
 
-def ask_for_manufacturer():
+def ask_for_manufacturer() -> str:
     logging.info("Who produced the device (e.g. LG)?")
     return pmb.helpers.cli.ask("Manufacturer", None, None, False)
 
 
-def ask_for_name(manufacturer):
+def ask_for_name(manufacturer: str) -> str:
     logging.info("What is the official name (e.g. Google Nexus 5)?")
     ret = pmb.helpers.cli.ask("Name", None, None, False)
 
@@ -47,13 +47,13 @@ def ask_for_name(manufacturer):
     return ret
 
 
-def ask_for_year():
+def ask_for_year() -> str:
     # Regex from https://stackoverflow.com/a/12240826
     logging.info("In what year was the device released (e.g. 2012)?")
     return pmb.helpers.cli.ask("Year", None, None, False, validation_regex=r"^[1-9]\d{3,}$")
 
 
-def ask_for_chassis():
+def ask_for_chassis() -> str:
     types = pmb.config.deviceinfo_chassis_types
 
     logging.info("What type of device is it?")
@@ -69,7 +69,7 @@ def ask_for_external_storage() -> bool:
     )
 
 
-def ask_for_flash_method():
+def ask_for_flash_method() -> str:
     while True:
         logging.info("Which flash method does the device support?")
         method = pmb.helpers.cli.ask(
@@ -100,7 +100,7 @@ def ask_for_flash_method():
         )
 
 
-def ask_for_bootimg():
+def ask_for_bootimg() -> Bootimg | None:
     logging.info(
         "You can analyze a known working boot.img file to"
         " automatically fill out the flasher information for your"
diff --git a/pmb/build/checksum.py b/pmb/build/checksum.py
index 18417e6b..660514bf 100644
--- a/pmb/build/checksum.py
+++ b/pmb/build/checksum.py
@@ -11,7 +11,7 @@ import pmb.helpers.pmaports
 from pmb.core import Chroot
 
 
-def update(pkgname):
+def update(pkgname: str) -> None:
     """Fetch all sources and update the checksums in the APKBUILD."""
     pmb.build.init_abuild_minimal()
     pmb.build.copy_to_buildpath(pkgname, no_override=True)
@@ -24,7 +24,7 @@ def update(pkgname):
     pmb.helpers.run.user(["cp", source, target])
 
 
-def verify(pkgname):
+def verify(pkgname: str) -> None:
     """Fetch all sources and verify their checksums."""
     pmb.build.init_abuild_minimal()
     pmb.build.copy_to_buildpath(pkgname)
diff --git a/pmb/build/envkernel.py b/pmb/build/envkernel.py
index 8f0c1462..78fbc729 100644
--- a/pmb/build/envkernel.py
+++ b/pmb/build/envkernel.py
@@ -21,7 +21,7 @@ from pmb.core import Chroot
 from pmb.core.context import get_context
 
 
-def match_kbuild_out(word):
+def match_kbuild_out(word: str) -> str | None:
     """Look for paths in the following formats:
       "<prefix>/<kbuild_out>/arch/<arch>/boot"
       "<prefix>/<kbuild_out>/include/config/kernel.release"
@@ -55,7 +55,7 @@ def match_kbuild_out(word):
     return "" if out_dir is None else out_dir.strip("/")
 
 
-def find_kbuild_output_dir(function_body):
+def find_kbuild_output_dir(function_body: list[str]) -> str:
     """Guess what the kernel build output directory is.
 
     Parses each line of the function word by word, looking for paths which
diff --git a/pmb/build/newapkbuild.py b/pmb/build/newapkbuild.py
index 4cb44994..168126a9 100644
--- a/pmb/build/newapkbuild.py
+++ b/pmb/build/newapkbuild.py
@@ -3,6 +3,7 @@
 import os
 from pmb.core.pkgrepo import pkgrepo_default_path
 from pmb.helpers import logging
+from pmb.types import PathString
 from pathlib import Path
 import pmb.chroot
 import pmb.helpers.cli
@@ -12,7 +13,7 @@ import pmb.build
 from pmb.core import Chroot
 
 
-def newapkbuild(folder, args_passed, force=False):
+def newapkbuild(folder: PathString, args_passed: list[str], force: bool = False) -> None:
     # Initialize build environment and build folder
     pmb.build.init()
     pmb.chroot.init(Chroot.native())
diff --git a/pmb/chroot/apk.py b/pmb/chroot/apk.py
index 34188714..4733965e 100644
--- a/pmb/chroot/apk.py
+++ b/pmb/chroot/apk.py
@@ -58,7 +58,7 @@ def check_min_version(chroot: Chroot = Chroot.native()) -> None:
     )
 
 
-def packages_split_to_add_del(packages):
+def packages_split_to_add_del(packages: list[str]) -> tuple[list[str], list[str]]:
     """
     Sort packages into "to_add" and "to_del" lists depending on their pkgname
     starting with an exclamation mark.
diff --git a/pmb/chroot/init.py b/pmb/chroot/init.py
index b36c2c27..38fad31f 100644
--- a/pmb/chroot/init.py
+++ b/pmb/chroot/init.py
@@ -59,7 +59,7 @@ def mark_in_chroot(chroot: Chroot = Chroot.native()) -> None:
         pmb.helpers.run.root(["touch", in_chroot_file])
 
 
-def init_keys():
+def init_keys() -> None:
     """
     All Alpine and postmarketOS repository keys are shipped with pmbootstrap.
     Copy them into $WORK/config_apk_keys, which gets mounted inside the various
diff --git a/pmb/chroot/initfs.py b/pmb/chroot/initfs.py
index 6bbdbba0..0f8b591f 100644
--- a/pmb/chroot/initfs.py
+++ b/pmb/chroot/initfs.py
@@ -77,7 +77,7 @@ def extract(flavor: str | None, chroot: Chroot, extra: bool = False) -> Path:
     return outside
 
 
-def ls(flavor, suffix, extra=False):
+def ls(flavor: str | None, suffix: Chroot, extra: bool = False) -> None:
     tmp = "/tmp/initfs-extracted"
     if extra:
         tmp = "/tmp/initfs-extra-extracted"
diff --git a/pmb/chroot/shutdown.py b/pmb/chroot/shutdown.py
index 4dff3dfc..5971b9f7 100644
--- a/pmb/chroot/shutdown.py
+++ b/pmb/chroot/shutdown.py
@@ -12,7 +12,7 @@ from pmb.core import Chroot, ChrootType
 from pmb.core.context import get_context
 
 
-def kill_adb():
+def kill_adb() -> None:
     """
     Kill adb daemon if it's running.
     """
@@ -22,7 +22,7 @@ def kill_adb():
             pmb.chroot.root(["adb", "-P", str(port), "kill-server"])
 
 
-def kill_sccache():
+def kill_sccache() -> None:
     """
     Kill sccache daemon if it's running. Unlike ccache it automatically spawns
     a daemon when you call it and exits after some time of inactivity.
@@ -59,7 +59,7 @@ def shutdown_cryptsetup_device(name: str) -> None:
         raise RuntimeError("Failed to parse 'cryptsetup status' output!")
 
 
-def shutdown(only_install_related=False):
+def shutdown(only_install_related: bool = False) -> None:
     # Stop daemons
     kill_adb()
     kill_sccache()
diff --git a/pmb/chroot/zap.py b/pmb/chroot/zap.py
index 813dcdfc..00348193 100644
--- a/pmb/chroot/zap.py
+++ b/pmb/chroot/zap.py
@@ -173,7 +173,7 @@ def zap_pkgs_local_mismatch(confirm: bool = True, dry: bool = False) -> None:
         pmb.build.other.index_repo()
 
 
-def zap_pkgs_online_mismatch(confirm=True, dry=False):
+def zap_pkgs_online_mismatch(confirm: bool = True, dry: bool = False) -> None:
     # Check whether we need to do anything
     paths = list(get_context().config.work.glob("cache_apk_*"))
     if not len(paths):
diff --git a/pmb/ci/__init__.py b/pmb/ci/__init__.py
index 8d6c9cd0..c8404346 100644
--- a/pmb/ci/__init__.py
+++ b/pmb/ci/__init__.py
@@ -5,13 +5,20 @@ import glob
 from pmb.helpers import logging
 import os
 from pathlib import Path
+from typing import Any, TypedDict
 import pmb.chroot
 from pmb.types import Env, PmbArgs
 import pmb.helpers.cli
 from pmb.core import Chroot
 
 
-def get_ci_scripts(topdir):
+class CiScriptDescriptor(TypedDict):
+    description: str
+    options: list[str]
+    artifacts: str | None
+
+
+def get_ci_scripts(topdir: Path) -> dict[str, CiScriptDescriptor]:
     """Find 'pmbootstrap ci'-compatible scripts inside a git repository, and
     parse their metadata (description, options). The reference is at:
     https://postmarketos.org/pmb-ci
@@ -21,7 +28,7 @@ def get_ci_scripts(topdir):
     :returns: a dict of CI scripts found in the git repository, e.g.
       {"ruff": {"description": "lint all python scripts", "options": []}, ...}
     """
-    ret = {}
+    ret: dict[str, CiScriptDescriptor] = {}
     for script in glob.glob(f"{topdir}/.ci/*.sh"):
         is_pmb_ci_script = False
         description = ""
@@ -61,7 +68,7 @@ def get_ci_scripts(topdir):
     return ret
 
 
-def sort_scripts_by_speed(scripts):
+def sort_scripts_by_speed(scripts: dict[str, CiScriptDescriptor]) -> dict[str, CiScriptDescriptor]:
     """Order the scripts, so fast scripts run before slow scripts. Whether a
     script is fast or not is determined by the '# Options: slow' comment in
     the file.
@@ -88,7 +95,9 @@ def sort_scripts_by_speed(scripts):
     return ret
 
 
-def ask_which_scripts_to_run(scripts_available):
+def ask_which_scripts_to_run(
+    scripts_available: dict[str, CiScriptDescriptor],
+) -> dict[str, CiScriptDescriptor]:
     """Display an interactive prompt about which of the scripts the user
     wishes to run, or all of them.
 
@@ -117,7 +126,7 @@ def ask_which_scripts_to_run(scripts_available):
     return ret
 
 
-def copy_git_repo_to_chroot(topdir):
+def copy_git_repo_to_chroot(topdir: Path) -> None:
     """Create a tarball of the git repo (including unstaged changes and new
     files) and extract it in chroot_native.
 
@@ -142,7 +151,7 @@ def copy_git_repo_to_chroot(topdir):
     pmb.chroot.user(["tar", "-xf", "/tmp/git.tar.gz"], working_dir=ci_dir)
 
 
-def run_scripts(topdir, scripts):
+def run_scripts(topdir: Path, scripts: dict[str, CiScriptDescriptor]) -> None:
     """Run one of the given scripts after another, either natively or in a
     chroot. Display a progress message and stop on error (without printing
     a python stack trace).
diff --git a/pmb/commands/base.py b/pmb/commands/base.py
index 42662c96..0f9bbcd6 100644
--- a/pmb/commands/base.py
+++ b/pmb/commands/base.py
@@ -5,6 +5,6 @@
 class Command:
     """Base class for pmbootstrap commands."""
 
-    def run(self):
+    def run(self) -> None:
         """Run the command."""
         raise NotImplementedError()
diff --git a/pmb/commands/index.py b/pmb/commands/index.py
index fe2af2fb..acffaa56 100644
--- a/pmb/commands/index.py
+++ b/pmb/commands/index.py
@@ -7,8 +7,8 @@ import pmb.build.other
 
 
 class Index(commands.Command):
-    def __init__(self):
+    def __init__(self) -> None:
         pass
 
-    def run(self):
+    def run(self) -> None:
         pmb.build.other.index_repo()
diff --git a/pmb/commands/kconfig.py b/pmb/commands/kconfig.py
index 94bce869..465ee5d3 100644
--- a/pmb/commands/kconfig.py
+++ b/pmb/commands/kconfig.py
@@ -96,6 +96,6 @@ class KConfigMigrate(commands.Command):
         self.pkgname_list = [pkgname] if isinstance(pkgname, str) else pkgname
         self.arch = arch
 
-    def run(self):
+    def run(self) -> None:
         for pkgname in self.pkgname_list:
             pmb.build.kconfig.migrate_config(pkgname, self.arch)
diff --git a/pmb/commands/repo_bootstrap.py b/pmb/commands/repo_bootstrap.py
index 7bb6a2e4..dffed1f1 100644
--- a/pmb/commands/repo_bootstrap.py
+++ b/pmb/commands/repo_bootstrap.py
@@ -26,7 +26,7 @@ class RepoBootstrap(commands.Command):
     progress_total: int = 0
     progress_step: str
 
-    def check_repo_arg(self):
+    def check_repo_arg(self) -> None:
         cfg = pmb.config.pmaports.read_config_repos()
 
         if self.repo in cfg:
@@ -79,7 +79,7 @@ class RepoBootstrap(commands.Command):
         if self.arch.cpu_emulation_required():
             self.progress_total += len(steps)
 
-    def log_progress(self, msg):
+    def log_progress(self, msg: str) -> None:
         percent = int(100 * self.progress_done / self.progress_total)
         logging.info(f"*** {percent}% [{self.progress_step}] {msg} ***")
 
@@ -130,7 +130,7 @@ class RepoBootstrap(commands.Command):
 
         self.log_progress("bootstrap complete!")
 
-    def check_existing_pkgs(self):
+    def check_existing_pkgs(self) -> None:
         channel = pmb.config.pmaports.read_config()["channel"]
         path = self.context.config.work / "packages" / channel / self.arch
 
@@ -169,7 +169,7 @@ class RepoBootstrap(commands.Command):
 
         return ret
 
-    def run(self):  # noqa: F821
+    def run(self) -> None:  # noqa: F821
         self.check_existing_pkgs()
 
         steps = self.get_steps()
diff --git a/pmb/commands/shutdown.py b/pmb/commands/shutdown.py
index 8f531be2..8df0895d 100644
--- a/pmb/commands/shutdown.py
+++ b/pmb/commands/shutdown.py
@@ -7,8 +7,8 @@ import pmb.chroot
 
 
 class Shutdown(commands.Command):
-    def __init__(self):
+    def __init__(self) -> None:
         pass
 
-    def run(self):
+    def run(self) -> None:
         pmb.chroot.shutdown()
diff --git a/pmb/commands/test.py b/pmb/commands/test.py
index 940b7b90..b06d5512 100644
--- a/pmb/commands/test.py
+++ b/pmb/commands/test.py
@@ -12,7 +12,7 @@ import time
 """Various internal test commands for performance testing and debugging."""
 
 
-def apkindex_parse_all():
+def apkindex_parse_all() -> None:
     indexes = pmb.helpers.repo.apkindex_files(Arch.native())
 
     pkgs = 0
@@ -26,9 +26,9 @@ def apkindex_parse_all():
 
 
 class Test(commands.Command):
-    def __init__(self, action: str):
+    def __init__(self, action: str) -> None:
         self.action = action
 
-    def run(self):
+    def run(self) -> None:
         if self.action == "apkindex_parse_all":
             apkindex_parse_all()
diff --git a/pmb/config/workdir.py b/pmb/config/workdir.py
index 1d4842aa..37871971 100644
--- a/pmb/config/workdir.py
+++ b/pmb/config/workdir.py
@@ -129,7 +129,7 @@ def chroot_check_channel(chroot: Chroot) -> bool:
     return False
 
 
-def clean():
+def clean() -> bool | None:
     """Remove obsolete data data from workdir.cfg.
 
     :returns: None if workdir does not exist,
diff --git a/pmb/core/config.py b/pmb/core/config.py
index 6c53216d..d30efb1d 100644
--- a/pmb/core/config.py
+++ b/pmb/core/config.py
@@ -83,7 +83,7 @@ class Config:
 
     providers: dict[str, str] = {}
 
-    def __init__(self):
+    def __init__(self) -> None:
         # Make sure we aren't modifying the class defaults
         for key in Config.__annotations__.keys():
             setattr(self, key, deepcopy(Config.get_default(key)))
diff --git a/pmb/helpers/apk.py b/pmb/helpers/apk.py
index 13172f18..29bf1c81 100644
--- a/pmb/helpers/apk.py
+++ b/pmb/helpers/apk.py
@@ -116,7 +116,7 @@ def _create_command_with_progress(command, fifo):
     return ["sh", "-c", command_flat]
 
 
-def _compute_progress(line):
+def _compute_progress(line: str) -> float:
     """Compute the progress as a number between 0 and 1.
 
     :param line: line as read from the progress fifo
@@ -277,7 +277,7 @@ def cache_clean(arch: Arch) -> None:
     pmb.helpers.run.root(_command)
 
 
-def check_outdated(version_installed, action_msg):
+def check_outdated(version_installed: str, action_msg: str) -> None:
     """Check if the provided alpine version is outdated.
 
     This depends on the alpine mirrordir (edge, v3.12, ...) related to currently checked out
diff --git a/pmb/helpers/apk_static.py b/pmb/helpers/apk_static.py
index 763f045b..6bc4115d 100644
--- a/pmb/helpers/apk_static.py
+++ b/pmb/helpers/apk_static.py
@@ -7,6 +7,7 @@ import shutil
 import tarfile
 import tempfile
 import stat
+from pathlib import Path
 
 import pmb.helpers.apk
 import pmb.helpers.run
@@ -19,7 +20,7 @@ import pmb.parse.version
 from pmb.core.context import get_context
 
 
-def read_signature_info(tar):
+def read_signature_info(tar: tarfile.TarFile) -> tuple[str, str]:
     """
     Find various information about the signature that was used to sign
     /sbin/apk.static inside the archive (not to be confused with the normal apk
@@ -107,7 +108,7 @@ def verify_signature(files, sigkey_path):
         )
 
 
-def extract(version, apk_path):
+def extract(version: str, apk_path: Path) -> None:
     """
     Extract everything to temporary locations, verify signatures and reported
     versions. When everything is right, move the extracted apk.static to the
@@ -147,7 +148,7 @@ def extract(version, apk_path):
     shutil.move(temp_path, target_path)
 
 
-def download(file):
+def download(file: str) -> Path:
     """
     Download a single file from an Alpine mirror.
     """
diff --git a/pmb/helpers/cli.py b/pmb/helpers/cli.py
index e24031be..3246f401 100644
--- a/pmb/helpers/cli.py
+++ b/pmb/helpers/cli.py
@@ -6,6 +6,8 @@ import os
 import re
 import readline
 import sys
+from collections.abc import KeysView
+from typing import Any
 
 import pmb.config
 from pmb.core.context import get_context
@@ -14,7 +16,7 @@ from pmb.core.context import get_context
 class ReadlineTabCompleter:
     """Store intermediate state for completer function."""
 
-    def __init__(self, options: list[str]) -> None:
+    def __init__(self, options: KeysView[str] | dict[str, Any] | list[str]) -> None:
         """:param options: list of possible completions."""
         self.options = sorted(options)
         self.matches: list[str] = []
@@ -38,13 +40,13 @@ class ReadlineTabCompleter:
 
 
 def ask(
-    question="Continue?",
-    choices=["y", "n"],
-    default="n",
-    lowercase_answer=True,
-    validation_regex=None,
-    complete=None,
-):
+    question: str = "Continue?",
+    choices: list[str] | None = ["y", "n"],
+    default: int | str | None = "n",
+    lowercase_answer: bool | None = True,
+    validation_regex: str | None = None,
+    complete: KeysView[str] | dict[str, Any] | list[str] | None = None,
+) -> str:
     """Ask a question on the terminal.
 
     :param question: display prompt
diff --git a/pmb/helpers/file.py b/pmb/helpers/file.py
index 858ce74e..ddc20cc9 100644
--- a/pmb/helpers/file.py
+++ b/pmb/helpers/file.py
@@ -84,7 +84,7 @@ def is_up_to_date(path_sources, path_target=None, lastmod_target=None):
     return lastmod_target >= lastmod_source
 
 
-def is_older_than(path, seconds):
+def is_older_than(path: Path, seconds: int) -> bool:
     """Check if a single file is older than a given amount of seconds."""
     if not os.path.exists(path):
         return True
diff --git a/pmb/helpers/package.py b/pmb/helpers/package.py
index 835d2876..4a720031 100644
--- a/pmb/helpers/package.py
+++ b/pmb/helpers/package.py
@@ -20,7 +20,7 @@ import pmb.helpers.pmaports
 import pmb.helpers.repo
 
 
-def remove_operators(package):
+def remove_operators(package: str) -> str:
     for operator in [">", ">=", "<=", "=", "<", "~"]:
         if operator in package:
             package = package.split(operator)[0]
diff --git a/pmb/helpers/pmaports.py b/pmb/helpers/pmaports.py
index 3ea6e08a..24932f9c 100644
--- a/pmb/helpers/pmaports.py
+++ b/pmb/helpers/pmaports.py
@@ -375,7 +375,7 @@ def get_channel_new(channel: str) -> str:
     return channel
 
 
-def require_bootstrap_error(repo, arch, trigger_str):
+def require_bootstrap_error(repo: str, arch: Arch, trigger_str: str) -> None:
     """
     Tell the user that they need to do repo_bootstrap, with some context.
 
@@ -392,7 +392,7 @@ def require_bootstrap_error(repo, arch, trigger_str):
     )
 
 
-def require_bootstrap(arch, trigger_str):
+def require_bootstrap(arch: Arch, trigger_str: str) -> None:
     """
     Check if repo_bootstrap was done, if any is needed.
 
diff --git a/pmb/helpers/repo_missing.py b/pmb/helpers/repo_missing.py
index 1692c768..e34fb7fb 100644
--- a/pmb/helpers/repo_missing.py
+++ b/pmb/helpers/repo_missing.py
@@ -1,16 +1,16 @@
 # Copyright 2023 Oliver Smith
 # SPDX-License-Identifier: GPL-3.0-or-later
-from typing import Any
 
 from pmb.core.arch import Arch
 from pmb.helpers import logging
+from pmb.types import Apkbuild
 
 import pmb.build
 import pmb.helpers.package
 import pmb.helpers.pmaports
 
 
-def filter_missing_packages(arch, pkgnames):
+def filter_missing_packages(arch: Arch, pkgnames: list[str]) -> list[str]:
     """Create a subset of pkgnames with missing or outdated binary packages.
 
     :param arch: architecture (e.g. "armhf")
@@ -27,7 +27,7 @@ def filter_missing_packages(arch, pkgnames):
     return ret
 
 
-def filter_aport_packages(pkgnames):
+def filter_aport_packages(pkgnames: list[str]) -> list[str]:
     """Create a subset of pkgnames where each one has an aport.
 
     :param pkgnames: list of package names (e.g. ["hello-world", "test12"])
@@ -40,7 +40,7 @@ def filter_aport_packages(pkgnames):
     return ret
 
 
-def filter_arch_packages(arch, pkgnames):
+def filter_arch_packages(arch: Arch, pkgnames: list[str]) -> list[str]:
     """Create a subset of pkgnames with packages removed that can not be built for a certain arch.
 
     :param arch: architecture (e.g. "armhf")
@@ -54,7 +54,7 @@ def filter_arch_packages(arch, pkgnames):
     return ret
 
 
-def get_relevant_packages(arch, pkgname=None, built=False):
+def get_relevant_packages(arch: Arch, pkgname: str | None = None, built: bool = False) -> list[str]:
     """Get all packages that can be built for the architecture in question.
 
     :param arch: architecture (e.g. "armhf")
@@ -92,7 +92,7 @@ def get_relevant_packages(arch, pkgname=None, built=False):
     return ret
 
 
-def generate_output_format(arch: Arch, pkgnames: list[str]) -> list[dict[str, Any]]:
+def generate_output_format(arch: Arch, pkgnames: list[str]) -> list[Apkbuild]:
     """Generate the detailed output format.
 
     :param arch: architecture
diff --git a/pmb/helpers/run_core.py b/pmb/helpers/run_core.py
index 3dabf486..ab8a8d94 100644
--- a/pmb/helpers/run_core.py
+++ b/pmb/helpers/run_core.py
@@ -72,7 +72,7 @@ def sanity_checks(
         raise RuntimeError("Can't use output_return with output: " + output)
 
 
-def background(cmd, working_dir=None):
+def background(cmd: str, working_dir: PathString | None = None) -> subprocess.Popen:
     """Run a subprocess in background and redirect its output to the log."""
     ret = subprocess.Popen(
         cmd, stdout=pmb.helpers.logging.logfd, stderr=pmb.helpers.logging.logfd, cwd=working_dir
@@ -81,7 +81,7 @@ def background(cmd, working_dir=None):
     return ret
 
 
-def pipe(cmd, working_dir=None):
+def pipe(cmd: str, working_dir: PathString | None = None) -> subprocess.Popen:
     """Run a subprocess in background and redirect its output to a pipe."""
     ret = subprocess.Popen(
         cmd,
@@ -156,7 +156,9 @@ def pipe_read(
         return
 
 
-def kill_process_tree(pid, ppids, sudo):
+# FIXME: The docstring claims that ppids should be a list of "process ID tuples", but in practice it
+# gets called with a list of string lists for the ppids argument.
+def kill_process_tree(pid: int | str, ppids: list[list[str]], sudo: bool) -> None:
     """Recursively kill a pid and its child processes.
 
     :param pid: process id that will be killed
@@ -173,7 +175,7 @@ def kill_process_tree(pid, ppids, sudo):
             kill_process_tree(child_pid, ppids, sudo)
 
 
-def kill_command(pid, sudo):
+def kill_command(pid: int, sudo: bool) -> None:
     """Kill a command process and recursively kill its child processes.
 
     :param pid: process id that will be killed
@@ -268,7 +270,7 @@ def foreground_pipe(
     return (process.returncode, b"".join(output_buffer).decode("utf-8"))
 
 
-def foreground_tui(cmd, working_dir=None):
+def foreground_tui(cmd: str, working_dir: PathString | None = None) -> int:
     """Run a subprocess in foreground without redirecting any of its output.
 
     This is the only way text-based user interfaces (ncurses programs like
@@ -279,7 +281,7 @@ def foreground_tui(cmd, working_dir=None):
     return process.wait()
 
 
-def check_return_code(code, log_message):
+def check_return_code(code: int, log_message: str) -> None:
     """Check the return code of a command.
 
     :param code: exit code to check
@@ -298,7 +300,7 @@ def check_return_code(code, log_message):
         raise RuntimeError(f"Command failed (exit code {str(code)}): " + log_message)
 
 
-def sudo_timer_iterate():
+def sudo_timer_iterate() -> None:
     """Run sudo -v and schedule a new timer to repeat the same."""
     if pmb.config.which_sudo() == "sudo":
         subprocess.Popen(["sudo", "-v"]).wait()
@@ -310,7 +312,7 @@ def sudo_timer_iterate():
     timer.start()
 
 
-def sudo_timer_start():
+def sudo_timer_start() -> None:
     """Start a timer to call sudo -v periodically, so that the password is only needed once."""
     if "sudo_timer_active" in pmb.helpers.other.cache:
         return
@@ -319,7 +321,7 @@ def sudo_timer_start():
     sudo_timer_iterate()
 
 
-def add_proxy_env_vars(env):
+def add_proxy_env_vars(env: Env) -> None:
     """Add proxy environment variables from host to the environment of the command we are running.
 
     :param env: dict of environment variables, it will be extended with all of the proxy env vars
diff --git a/pmb/helpers/ui.py b/pmb/helpers/ui.py
index 5eeb88d5..c56229f3 100644
--- a/pmb/helpers/ui.py
+++ b/pmb/helpers/ui.py
@@ -1,6 +1,7 @@
 # Copyright 2023 Clayton Craft
 # SPDX-License-Identifier: GPL-3.0-or-later
 import os
+from pmb.core.arch import Arch
 from pmb.core.pkgrepo import pkgrepo_iglob
 from pmb.types import WithExtraRepos
 import pmb.helpers.pmaports
@@ -8,7 +9,7 @@ import pmb.helpers.package
 import pmb.parse
 
 
-def list_ui(arch):
+def list_ui(arch: Arch) -> list[tuple[str, str]]:
     """Get all UIs, for which aports are available with their description.
 
     :param arch: device architecture, for which the UIs must be available
diff --git a/pmb/install/_install.py b/pmb/install/_install.py
index dd9381d3..5d196b9f 100644
--- a/pmb/install/_install.py
+++ b/pmb/install/_install.py
@@ -673,7 +673,7 @@ def write_cgpt_kpart(args: PmbArgs, layout: PartitionLayout, suffix: Chroot) ->
     pmb.chroot.root(["dd", f"if={filename}", f"of=/dev/installp{layout['kernel']}"])
 
 
-def sanity_check_boot_size():
+def sanity_check_boot_size() -> None:
     default = Config().boot_size
     config = get_context().config
     if int(config.boot_size) >= int(default):
diff --git a/pmb/install/format.py b/pmb/install/format.py
index 72e2bc73..c0276d24 100644
--- a/pmb/install/format.py
+++ b/pmb/install/format.py
@@ -6,7 +6,7 @@ from pmb.core import Chroot
 from pmb.types import PartitionLayout, PmbArgs, PathString
 
 
-def install_fsprogs(filesystem):
+def install_fsprogs(filesystem: str) -> None:
     """Install the package required to format a specific filesystem."""
     fsprogs = pmb.config.filesystems.get(filesystem)
     if not fsprogs:
diff --git a/pmb/meta/__init__.py b/pmb/meta/__init__.py
index e3c3594b..75f23693 100644
--- a/pmb/meta/__init__.py
+++ b/pmb/meta/__init__.py
@@ -12,7 +12,7 @@ FuncReturn = TypeVar("FuncReturn")
 
 
 class Wrapper(Generic[FuncArgs, FuncReturn]):
-    def __init__(self, cache: "Cache", func: Callable[[FuncArgs], FuncReturn]):
+    def __init__(self, cache: "Cache", func: Callable[[FuncArgs], FuncReturn]) -> None:
         self.cache = cache
         self.func = func
         self.disabled = False
@@ -47,12 +47,12 @@ class Wrapper(Generic[FuncArgs, FuncReturn]):
 
         return self.cache.cache[key]
 
-    def cache_clear(self):
+    def cache_clear(self) -> None:
         self.cache.clear()
         self.misses = 0
         self.hits = 0
 
-    def cache_disable(self):
+    def cache_disable(self) -> None:
         self.disabled = True
 
 
@@ -64,7 +64,7 @@ class Cache:
     function is called with the given value. For example, in pmb.build._package
     we never want to use the cached result when called with force=True."""
 
-    def __init__(self, *args, cache_deepcopy=False, **kwargs):
+    def __init__(self, *args: str, cache_deepcopy: bool = False, **kwargs: Any) -> None:
         for a in args:
             if not isinstance(a, str):
                 raise ValueError(f"Cache key must be a string, not {type(a)}")
@@ -72,7 +72,7 @@ class Cache:
         if len(args) != len(set(args)):
             raise ValueError("Duplicate cache key properties")
 
-        self.cache = {}
+        self.cache: dict[str, Any] = {}
         self.params = args
         self.kwargs = kwargs
         self.cache_deepcopy = cache_deepcopy
@@ -144,5 +144,5 @@ class Cache:
         # FIXME: Once PEP-695 generics are in we shouldn't need this.
         return Wrapper(self, func)
 
-    def clear(self):
+    def clear(self) -> None:
         self.cache.clear()
diff --git a/pmb/parse/arguments.py b/pmb/parse/arguments.py
index c6eecd02..efdcee52 100644
--- a/pmb/parse/arguments.py
+++ b/pmb/parse/arguments.py
@@ -29,7 +29,9 @@ import pmb.helpers.pmaports
 """
 
 
-def toggle_other_boolean_flags(*other_destinations, value=True):
+def toggle_other_boolean_flags(
+    *other_destinations: str, value: bool = True
+) -> type[argparse.Action]:
     """Group several argparse flags to one.
 
     Sets multiple other_destination to value.
@@ -52,12 +54,12 @@ def toggle_other_boolean_flags(*other_destinations, value=True):
     return SetOtherDestinationsAction
 
 
-def type_ondev_cp(val):
+def type_ondev_cp(val: str) -> list[str]:
     """Parse and validate arguments to 'pmbootstrap install --ondev --cp'.
 
     :param val: 'HOST_SRC:CHROOT_DEST' string
 
-    :returns: (HOST_SRC, CHROOT_DEST)
+    :returns: [HOST_SRC, CHROOT_DEST]
     """
     ret = val.split(":")
 
@@ -75,7 +77,7 @@ def type_ondev_cp(val):
     return ret
 
 
-def arguments_install(subparser):
+def arguments_install(subparser: argparse._SubParsersAction) -> None:
     ret = subparser.add_parser(
         "install", help="set up device specific chroot and install to SD card or image file"
     )
@@ -266,7 +268,7 @@ def arguments_install(subparser):
     )
 
 
-def arguments_export(subparser):
+def arguments_export(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser(
         "export",
         help="create convenience symlinks"
@@ -297,7 +299,7 @@ def arguments_export(subparser):
     return ret
 
 
-def arguments_sideload(subparser):
+def arguments_sideload(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser(
         "sideload", help="Push packages to a running phone connected over usb or wifi"
     )
@@ -325,7 +327,7 @@ def arguments_sideload(subparser):
     return ret
 
 
-def arguments_flasher(subparser):
+def arguments_flasher(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser("flasher", help="flash something to the target device")
     ret.add_argument("--method", help="override flash method", dest="flash_method", default=None)
     sub = ret.add_subparsers(dest="action_flasher")
@@ -431,7 +433,7 @@ def arguments_flasher(subparser):
     return ret
 
 
-def arguments_initfs(subparser):
+def arguments_initfs(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser("initfs", help="do something with the initramfs")
     sub = ret.add_subparsers(dest="action_initfs")
 
@@ -457,7 +459,7 @@ def arguments_initfs(subparser):
     return ret
 
 
-def arguments_qemu(subparser):
+def arguments_qemu(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser("qemu")
     ret.add_argument("--cmdline", help="override kernel commandline")
     ret.add_argument(
@@ -549,7 +551,7 @@ def arguments_qemu(subparser):
     return ret
 
 
-def arguments_pkgrel_bump(subparser):
+def arguments_pkgrel_bump(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser(
         "pkgrel_bump",
         help="increase the pkgrel to"
@@ -577,7 +579,7 @@ def arguments_pkgrel_bump(subparser):
     return ret
 
 
-def arguments_pkgver_bump(subparser):
+def arguments_pkgver_bump(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser(
         "pkgver_bump",
         help="increase the pkgver and reset pkgrel to 0. useful when dealing with metapackages.",
@@ -587,7 +589,7 @@ def arguments_pkgver_bump(subparser):
     return ret
 
 
-def arguments_aportupgrade(subparser):
+def arguments_aportupgrade(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser(
         "aportupgrade", help="check for outdated packages that need upgrading"
     )
@@ -609,7 +611,7 @@ def arguments_aportupgrade(subparser):
     return ret
 
 
-def arguments_newapkbuild(subparser):
+def arguments_newapkbuild(subparser: argparse._SubParsersAction) -> None:
     """
     Wrapper for Alpine's "newapkbuild" command.
 
@@ -651,7 +653,7 @@ def arguments_newapkbuild(subparser):
     )
 
 
-def arguments_kconfig(subparser):
+def arguments_kconfig(subparser: argparse._SubParsersAction) -> None:
     # Allowed architectures
     arch_choices = Arch.supported()
 
@@ -726,7 +728,7 @@ def arguments_repo_bootstrap(subparser):
     return ret
 
 
-def arguments_repo_missing(subparser):
+def arguments_repo_missing(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser("repo_missing")
     package = ret.add_argument(
         "package", nargs="?", help="only look at a specific package and its dependencies"
@@ -745,23 +747,23 @@ def arguments_repo_missing(subparser):
     return ret
 
 
-def arguments_lint(subparser):
+def arguments_lint(subparser: argparse._SubParsersAction) -> None:
     lint = subparser.add_parser("lint", help="run quality checks on pmaports (required to pass CI)")
     add_packages_arg(lint, nargs="*")
 
 
-def arguments_test(subparser):
+def arguments_test(subparser: argparse._SubParsersAction) -> None:
     test = subparser.add_parser("test", help="Internal pmbootstrap test tools")
     sub = test.add_subparsers(dest="action_test", required=True)
     sub.add_parser("apkindex_parse_all", help="parse all APKINDEX files")
 
 
-def arguments_status(subparser):
+def arguments_status(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser("status", help="show a config and pmaports overview")
     return ret
 
 
-def arguments_netboot(subparser):
+def arguments_netboot(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser("netboot", help="launch nbd server with pmOS rootfs")
     sub = ret.add_subparsers(dest="action_netboot")
     sub.required = True
@@ -772,7 +774,7 @@ def arguments_netboot(subparser):
     return ret
 
 
-def arguments_ci(subparser):
+def arguments_ci(subparser: argparse._SubParsersAction) -> argparse.ArgumentParser:
     ret = subparser.add_parser(
         "ci",
         help="run continuous integration scripts locally of git repo in current directory",
@@ -1294,7 +1296,7 @@ def get_parser():
     return parser
 
 
-def arguments():
+def arguments() -> PmbArgs:
     args: PmbArgs = get_parser().parse_args()
 
     if getattr(args, "fork_alpine_retain_branch", False):
diff --git a/pmb/parse/binfmt_info.py b/pmb/parse/binfmt_info.py
index 4a1d6dc0..96c866e1 100644
--- a/pmb/parse/binfmt_info.py
+++ b/pmb/parse/binfmt_info.py
@@ -7,7 +7,8 @@ import pmb.config
 # Return: {magic: ..., mask: ...}
 
 
-def binfmt_info(arch_qemu):
+# FIXME: Maybe this should use Arch instead of str.
+def binfmt_info(arch_qemu: str) -> dict[str, str]:
     # Parse the info file
     full = {}
     info = pmb.config.pmb_src / "pmb/data/qemu-user-binfmt.txt"
diff --git a/pmb/parse/kconfig.py b/pmb/parse/kconfig.py
index be6bf093..f663dead 100644
--- a/pmb/parse/kconfig.py
+++ b/pmb/parse/kconfig.py
@@ -4,6 +4,7 @@ from pathlib import Path
 from pmb.helpers import logging
 import re
 import os
+from typing import Literal, overload
 
 import pmb.build
 import pmb.config
@@ -14,7 +15,7 @@ from pmb.helpers.exceptions import NonBugError
 from pmb.types import PathString
 
 
-def is_set(config, option):
+def is_set(config: str, option: str) -> bool:
     """
     Check, whether a boolean or tristate option is enabled
     either as builtin or module.
@@ -26,7 +27,7 @@ def is_set(config, option):
     return re.search("^CONFIG_" + option + "=[ym]$", config, re.M) is not None
 
 
-def is_set_str(config, option, string):
+def is_set_str(config: str, option: str, string: str) -> bool:
     """
     Check, whether a config option contains a string as value.
 
@@ -42,7 +43,7 @@ def is_set_str(config, option, string):
         return False
 
 
-def is_in_array(config, option, string):
+def is_in_array(config: str, option: str, string: str) -> bool:
     """
     Check, whether a config option contains string as an array element
 
@@ -59,7 +60,14 @@ def is_in_array(config, option, string):
         return False
 
 
-def check_option(component, details, config, config_path, option, option_value):
+def check_option(
+    component: str,
+    details: bool,
+    config: str,
+    config_path: PathString,
+    option: str,
+    option_value: bool | str | list[str],
+) -> bool:
     """
     Check, whether one kernel config option has a given value.
 
@@ -72,7 +80,7 @@ def check_option(component, details, config, config_path, option, option_value):
     :returns: True if the check passed, False otherwise
     """
 
-    def warn_ret_false(should_str):
+    def warn_ret_false(should_str: str) -> bool:
         config_name = os.path.basename(config_path)
         if details:
             logging.warning(
@@ -107,8 +115,14 @@ def check_option(component, details, config, config_path, option, option_value):
 
 
 def check_config_options_set(
-    config, config_path, config_arch, options, component, pkgver, details=False
-):
+    config: str,
+    config_path: PathString,
+    config_arch: str,  # TODO: Replace with Arch type?
+    options: dict[str, dict],
+    component: str,
+    pkgver: str,
+    details: bool = False,
+) -> bool:
     """
     Check, whether all the kernel config passes all rules of one component.
 
@@ -195,7 +209,27 @@ def check_config(
     return all(ret)
 
 
-def check(pkgname, components_list=[], details=False, must_exist=True):
+@overload
+def check(
+    pkgname: str,
+    components_list: list[str] = ...,
+    details: bool = ...,
+    must_exist: Literal[False] = ...,
+) -> bool | None: ...
+
+
+@overload
+def check(
+    pkgname: str,
+    components_list: list[str] = ...,
+    details: bool = ...,
+    must_exist: Literal[True] = ...,
+) -> bool: ...
+
+
+def check(
+    pkgname: str, components_list: list[str] = [], details: bool = False, must_exist: bool = True
+) -> bool | None:
     """
     Check for necessary kernel config options in a package.
 
@@ -263,7 +297,8 @@ def check(pkgname, components_list=[], details=False, must_exist=True):
     return ret
 
 
-def extract_arch(config_path):
+# TODO: Make this use the Arch type probably
+def extract_arch(config_path: PathString) -> str:
     # Extract the architecture out of the config
     with open(config_path) as f:
         config = f.read()
@@ -283,7 +318,7 @@ def extract_arch(config_path):
     return "unknown"
 
 
-def extract_version(config_path):
+def extract_version(config_path: PathString) -> str:
     # Try to extract the version string out of the comment header
     with open(config_path) as f:
         # Read the first 3 lines of the file and get the third line only
diff --git a/pmb/parse/version.py b/pmb/parse/version.py
index c7840453..4a727a1b 100644
--- a/pmb/parse/version.py
+++ b/pmb/parse/version.py
@@ -10,7 +10,7 @@ https://git.alpinelinux.org/cgit/apk-tools/tree/src/version.c
 """
 
 
-def token_value(string):
+def token_value(string: str) -> int:
     """
     Return the associated value for a given token string (we parse
     through the version string one token at a time).
@@ -35,7 +35,7 @@ def token_value(string):
     return order[string]
 
 
-def next_token(previous, rest):
+def next_token(previous: str, rest: str) -> tuple[str, str]:
     """
     Parse the next token in the rest of the version string, we're
     currently looking at.
@@ -90,7 +90,7 @@ def next_token(previous, rest):
     return (next, rest)
 
 
-def parse_suffix(rest):
+def parse_suffix(rest: str) -> tuple[str, int, bool]:
     """
     Cut off the suffix of rest (which is now at the beginning of the
     rest variable, but regarding the whole version string, it is a
@@ -188,7 +188,7 @@ def get_token(previous, rest):
     return (next, value, rest)
 
 
-def validate(version):
+def validate(version: str) -> bool:
     """
     Check whether one version string is valid.
 
@@ -277,7 +277,7 @@ Convenience functions below are not modeled after apk's version.c.
 """
 
 
-def check_string(a_version, rule):
+def check_string(a_version: str, rule: str) -> bool:
     """
     Compare a version against a check string. This is used in "pmbootstrap
     kconfig check", to only require certain options if the pkgver is in a
diff --git a/pmb/qemu/run.py b/pmb/qemu/run.py
index be12183e..6f16e8e7 100644
--- a/pmb/qemu/run.py
+++ b/pmb/qemu/run.py
@@ -287,7 +287,7 @@ def command_qemu(
     return (command, env)
 
 
-def resize_image(img_size_new, img_path):
+def resize_image(img_size_new: str, img_path: Path) -> None:
     """
     Truncates an image to a specific size. The value must be larger than the
     current image size, and it must be specified in MiB or GiB units (powers of