diff --git a/backportpackage b/backportpackage
index 2896617..906ab0e 100755
--- a/backportpackage
+++ b/backportpackage
@@ -25,6 +25,7 @@ import shutil
 import subprocess
 import sys
 import tempfile
+from typing import Any, NoReturn
 from urllib.parse import quote
 
 try:
@@ -50,7 +51,7 @@ from ubuntutools.question import YesNoQuestion
 Logger = getLogger()
 
 
-def error(msg, *args):
+def error(msg: str, *args: Any) -> NoReturn:
     Logger.error(msg, *args)
     sys.exit(1)
 
diff --git a/lp-bitesize b/lp-bitesize
index 0308164..1f96f85 100755
--- a/lp-bitesize
+++ b/lp-bitesize
@@ -23,6 +23,7 @@
 
 import argparse
 import sys
+from typing import Any, NoReturn
 
 from launchpadlib.errors import HTTPError
 from launchpadlib.launchpad import Launchpad
@@ -33,7 +34,7 @@ from ubuntutools.config import UDTConfig
 Logger = getLogger()
 
 
-def error_out(msg, *args):
+def error_out(msg: str, *args: Any) -> NoReturn:
     Logger.error(msg, *args)
     sys.exit(1)
 
diff --git a/merge-changelog b/merge-changelog
index b02474a..a05473d 100755
--- a/merge-changelog
+++ b/merge-changelog
@@ -22,6 +22,7 @@
 # pylint: enable=invalid-name
 
 import sys
+from typing import NoReturn
 
 from debian.changelog import Changelog
 
@@ -30,7 +31,7 @@ from ubuntutools import getLogger
 Logger = getLogger()
 
 
-def usage(exit_code=1):
+def usage(exit_code: int = 1) -> NoReturn:
     Logger.info(
         """Usage: merge-changelog <left changelog> <right changelog>
 
diff --git a/pbuilder-dist b/pbuilder-dist
index 4d1ad84..d2040ce 100755
--- a/pbuilder-dist
+++ b/pbuilder-dist
@@ -38,6 +38,7 @@ import shutil
 import subprocess
 import sys
 from contextlib import suppress
+from typing import NoReturn
 
 import debian.deb822
 from distro_info import DebianDistroInfo, DistroDataOutdated, UbuntuDistroInfo
@@ -411,7 +412,7 @@ class PbuilderDist:
         ] + arguments
 
 
-def show_help(exit_code=0):
+def show_help(exit_code: int = 0) -> NoReturn:
     """help() -> None
 
     Print a help message for pbuilder-dist, and exit with the given code.
diff --git a/ubuntutools/sponsor_patch/question.py b/ubuntutools/sponsor_patch/question.py
index 56afc9d..b4d81d9 100644
--- a/ubuntutools/sponsor_patch/question.py
+++ b/ubuntutools/sponsor_patch/question.py
@@ -16,6 +16,7 @@
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 import sys
+from typing import NoReturn
 
 from ubuntutools.question import Question, YesNoQuestion
 
@@ -42,7 +43,7 @@ def ask_for_manual_fixing():
         user_abort()
 
 
-def user_abort():
+def user_abort() -> NoReturn:
     """Print abort and quit the program."""
 
     print("User abort.")