diff --git a/dev_scripts/env.py b/dev_scripts/env.py
index 31c6543..af68c7a 100755
--- a/dev_scripts/env.py
+++ b/dev_scripts/env.py
@@ -115,7 +115,7 @@ DOCKERFILE_UBUNTU_REM_USER = r"""
 RUN touch /var/mail/ubuntu && chown ubuntu /var/mail/ubuntu && userdel -r ubuntu
 """
 
-# On Ubuntu Jammy / Debian Bullseye, use a different conmon version, as acquired from
+# On Ubuntu Jammy, use a different conmon version, as acquired from
 # Debian's oldstable proposed updates. For more details, read:
 # https://github.com/freedomofpress/dangerzone/issues/685
 DOCKERFILE_CONMON_UPDATE = r"""
@@ -565,8 +565,8 @@ class Env:
                 # Ubuntu Jammy misses a dependency to `libxkbcommon-x11-0`, which we can
                 # install indirectly via `qt6-qpa-plugins`.
                 qt_deps += " qt6-qpa-plugins"
-                # Ubuntu Jammy and Debian Bullseye require a more up-to-date conmon
-                # package (see https://github.com/freedomofpress/dangerzone/issues/685)
+                # Ubuntu Jammy requires a more up-to-date conmon package
+                # (see https://github.com/freedomofpress/dangerzone/issues/685)
                 install_deps = (
                     DOCKERFILE_CONMON_UPDATE + DOCKERFILE_BUILD_DEV_DEBIAN_DEPS
                 )
@@ -582,11 +582,6 @@ class Env:
             elif self.distro == "debian" and self.version in ("bullseye-backports",):
                 # Debian Bullseye misses a dependency to libgl1.
                 qt_deps += " libgl1"
-                # Ubuntu Jammy and Debian Bullseye require a more up-to-date conmon
-                # package (see https://github.com/freedomofpress/dangerzone/issues/685)
-                install_deps = (
-                    DOCKERFILE_CONMON_UPDATE + DOCKERFILE_BUILD_DEV_DEBIAN_DEPS
-                )
 
             install_deps = install_deps.format(qt_deps=qt_deps)
 
@@ -604,7 +599,7 @@ class Env:
         shutil.copy(git_root() / "pyproject.toml", build_dir)
         shutil.copy(git_root() / "poetry.lock", build_dir)
         shutil.copy(git_root() / "dev_scripts" / "storage.conf", build_dir)
-        if self.distro in ("debian", "ubuntu"):
+        if self.distro == "ubuntu":
             shutil.copy(git_root() / "dev_scripts" / "oldstable-pu.pref", build_dir)
             shutil.copy(
                 git_root() / "dev_scripts" / f"oldstable-pu-{self.distro}.sources",
@@ -660,10 +655,8 @@ class Env:
                 install_deps = (
                     DOCKERFILE_UBUNTU_2004_DEPS + DOCKERFILE_BUILD_DEBIAN_DEPS
                 )
-            elif (self.distro == "ubuntu" and self.version in ("22.04", "jammy")) or (
-                self.distro == "debian" and self.version in ("bullseye-backports",)
-            ):
-                # Ubuntu Jammy and Debian Bullseye require a more up-to-date conmon
+            elif self.distro == "ubuntu" and self.version in ("22.04", "jammy"):
+                # Ubuntu Jammy requires a more up-to-date conmon
                 # package (see https://github.com/freedomofpress/dangerzone/issues/685)
                 install_deps = DOCKERFILE_CONMON_UPDATE + DOCKERFILE_BUILD_DEBIAN_DEPS
             elif self.distro == "ubuntu" and self.version in (
@@ -694,7 +687,7 @@ class Env:
         # Populate the build context.
         shutil.copy(package_src, package_dst)
         shutil.copy(git_root() / "dev_scripts" / "storage.conf", build_dir)
-        if self.distro in ("debian", "ubuntu"):
+        if self.distro == "ubuntu":
             shutil.copy(git_root() / "dev_scripts" / "oldstable-pu.pref", build_dir)
             shutil.copy(
                 git_root() / "dev_scripts" / f"oldstable-pu-{self.distro}.sources",
diff --git a/dev_scripts/oldstable-pu-debian.sources b/dev_scripts/oldstable-pu-debian.sources
deleted file mode 100644
index ba4e3da..0000000
--- a/dev_scripts/oldstable-pu-debian.sources
+++ /dev/null
@@ -1,4 +0,0 @@
-Types: deb
-URIs: http://deb.debian.org/debian/
-Suites: oldstable-proposed-updates
-Components: main