diff --git a/dev_scripts/env.py b/dev_scripts/env.py
index f75cc5016..8f21ddacd 100755
--- a/dev_scripts/env.py
+++ b/dev_scripts/env.py
@@ -317,15 +317,28 @@ def get_current_date():
     return date.today().strftime("%Y-%m-%d")
 
 
+def get_build_dir_sources(distro, version):
+    """Return the files needed to build an image."""
+    sources = [
+        git_root() / "pyproject.toml",
+        git_root() / "poetry.lock",
+        git_root() / "dev_scripts" / "storage.conf",
+        git_root() / "dev_scripts" / "containers.conf",
+    ]
+
+    if distro == "ubuntu" and version in ("22.04", "jammy"):
+        sources.extend(
+            [
+                git_root() / "dev_scripts" / "apt-tools-prod.pref",
+                git_root() / "dev_scripts" / "apt-tools-prod.sources",
+            ]
+        )
+    return sources
+
+
 def image_name_build_dev(distro, version):
     """Get the container image for the dev variant of a Dangerzone environment."""
-    hash = hash_files(
-        get_files_in("dev_scripts")
-        + [
-            git_root() / "pyproject.toml",
-            git_root() / "poetry.lock",
-        ]
-    )
+    hash = hash_files(get_build_dir_sources(distro, version))
 
     return IMAGE_NAME_BUILD_DEV_FMT.format(
         distro=distro, version=version, hash=hash, date=get_current_date()
@@ -695,15 +708,9 @@ def build_dev(self, show_dockerfile=DEFAULT_SHOW_DOCKERFILE, sync=False):
         os.makedirs(build_dir, exist_ok=True)
 
         # Populate the build context.
-        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)
-        shutil.copy(git_root() / "dev_scripts" / "containers.conf", build_dir)
-        if self.distro == "ubuntu" and self.version in ("22.04", "jammy"):
-            shutil.copy(git_root() / "dev_scripts" / "apt-tools-prod.pref", build_dir)
-            shutil.copy(
-                git_root() / "dev_scripts" / "apt-tools-prod.sources", build_dir
-            )
+        for source in get_build_dir_sources(self.distro, self.version):
+            shutil.copy(source, build_dir)
+
         with open(build_dir / "Dockerfile", mode="w") as f:
             f.write(dockerfile)