diff --git a/Payload_img_design.md b/Payload_img_design.md
index 6bfc34a9..d998ff2b 100644
--- a/Payload_img_design.md
+++ b/Payload_img_design.md
@@ -104,5 +104,5 @@ Attach `external.img` as an extra raw disk in QEMU, or as the second disk on bar
 - Without `--external-sources` and without `--repo`, there is no second disk:
   the initial image only includes distfiles needed before `improve: get_network`,
   and later distfiles are downloaded from mirrors.
-- `--build-guix-also` increases container contents (includes post-early `steps-guix`
+- `--extra-builds=guix` increases container contents (includes post-early `steps-guix`
   sources), but does not change the mechanism.
diff --git a/README.rst b/README.rst
index e1380d39..b2379a23 100644
--- a/README.rst
+++ b/README.rst
@@ -135,7 +135,7 @@ with ``--external-sources`` (and no ``--repo``).
 Notes:
 
 * ``external.img`` raw container mode is used with ``--external-sources`` (and
-  no ``--repo``). With ``--build-guix-also``, the container content is larger
+  no ``--repo``). With ``--extra-builds=guix``, the container content is larger
   because it also includes post-early sources from ``steps-guix``.
 * Without ``--external-sources`` and without ``--repo``, there is no second
   image. The initial image only includes distfiles needed before
diff --git a/lib/generator.py b/lib/generator.py
index c8487d0f..187a1790 100755
--- a/lib/generator.py
+++ b/lib/generator.py
@@ -30,24 +30,24 @@ class Generator():
 
     # pylint: disable=too-many-arguments,too-many-positional-arguments
     def __init__(self, arch, external_sources, early_preseed, repo_path, mirrors,
-                 build_guix_also=False):
+                 extra_builds=None):
         self.arch = arch
         self.early_preseed = early_preseed
         self.external_sources = external_sources
         self.repo_path = repo_path
         self.mirrors = mirrors
-        self.build_guix_also = build_guix_also
+        self.extra_builds = list(extra_builds or [])
         self.pre_network_source_manifest = self.get_source_manifest(
             stop_before_improve="get_network",
-            build_guix_also=False,
+            extra_builds=[],
         )
         self.pre_import_source_manifest = self.get_source_manifest(
             stop_before_improve="import_payload",
-            build_guix_also=False,
+            extra_builds=[],
         )
         # Only raw-external mode needs full upfront availability for container generation.
         if self.external_sources and not self.repo_path:
-            self.source_manifest = self.get_source_manifest(build_guix_also=self.build_guix_also)
+            self.source_manifest = self.get_source_manifest(extra_builds=self.extra_builds)
         else:
             self.source_manifest = self.pre_network_source_manifest
         self.bootstrap_source_manifest = self.source_manifest
@@ -98,7 +98,7 @@ class Generator():
         # carrier for the remaining distfiles.
         self.bootstrap_source_manifest = self.pre_import_source_manifest
 
-        full_manifest = self.get_source_manifest(build_guix_also=self.build_guix_also)
+        full_manifest = self.get_source_manifest(extra_builds=self.extra_builds)
         if self.bootstrap_source_manifest == full_manifest:
             raise ValueError("steps/manifest must include `improve: import_payload` in kernel-bootstrap mode.")
         bootstrap_set = set(self.bootstrap_source_manifest)
@@ -255,13 +255,18 @@ class Generator():
         self.get_packages()
 
         shutil.copytree(os.path.join(self.git_dir, 'steps'), os.path.join(self.target_dir, 'steps'))
-        if self.build_guix_also:
-            steps_guix_dir = os.path.join(self.git_dir, 'steps-guix')
-            if not os.path.isdir(steps_guix_dir):
-                raise ValueError("steps-guix directory does not exist while --build-guix-also is set.")
-            if not os.path.isfile(os.path.join(steps_guix_dir, 'manifest')):
-                raise ValueError("steps-guix/manifest does not exist while --build-guix-also is set.")
-            shutil.copytree(steps_guix_dir, os.path.join(self.target_dir, 'steps-guix'))
+        for extra_build in self.extra_builds:
+            steps_extra = f"steps-{extra_build}"
+            steps_extra_dir = os.path.join(self.git_dir, steps_extra)
+            if not os.path.isdir(steps_extra_dir):
+                raise ValueError(
+                    f"{steps_extra} directory does not exist while --extra-builds includes {extra_build}."
+                )
+            if not os.path.isfile(os.path.join(steps_extra_dir, 'manifest')):
+                raise ValueError(
+                    f"{steps_extra}/manifest does not exist while --extra-builds includes {extra_build}."
+                )
+            shutil.copytree(steps_extra_dir, os.path.join(self.target_dir, steps_extra))
 
     def stage0_posix(self, kernel_bootstrap=False):
         """Copy in all of the stage0-posix"""
@@ -488,25 +493,27 @@ this script the next time")
             self.check_file(path, line[0])
 
     @classmethod
-    def get_source_manifest(cls, stop_before_improve=None, build_guix_also=False):
+    def get_source_manifest(cls, stop_before_improve=None, extra_builds=None):
         """
         Generate a source manifest for the system.
         """
         entries = []
         directory = os.path.relpath(cls.distfiles_dir, cls.git_dir)
+        extra_builds = list(extra_builds or [])
 
         manifests = [os.path.join(cls.git_dir, 'steps')]
-        if build_guix_also:
-            steps_guix_dir = os.path.join(cls.git_dir, 'steps-guix')
-            if not os.path.isdir(steps_guix_dir):
-                raise ValueError("steps-guix directory does not exist while --build-guix-also is set.")
-            manifests.append(steps_guix_dir)
+        for extra_build in extra_builds:
+            steps_extra = f"steps-{extra_build}"
+            steps_extra_dir = os.path.join(cls.git_dir, steps_extra)
+            if not os.path.isdir(steps_extra_dir):
+                raise ValueError(
+                    f"{steps_extra} directory does not exist while --extra-builds includes {extra_build}."
+                )
+            manifests.append(steps_extra_dir)
 
         for steps_dir in manifests:
             manifest_path = os.path.join(steps_dir, 'manifest')
             if not os.path.isfile(manifest_path):
-                if steps_dir.endswith('steps-guix'):
-                    raise ValueError("steps-guix/manifest does not exist while --build-guix-also is set.")
                 raise ValueError(f"Missing manifest: {manifest_path}")
 
             with open(manifest_path, 'r', encoding="utf_8") as file:
diff --git a/rootfs.py b/rootfs.py
index 00c86150..8bdf2d40 100755
--- a/rootfs.py
+++ b/rootfs.py
@@ -314,8 +314,7 @@ def _update_stage0_tree(mountpoint,
     with open(old_config_path, "r", encoding="utf-8") as cfg:
         lines = [
             line for line in cfg
-            if not line.startswith("BUILD_GUIX_ALSO=")
-            and not line.startswith("EXTRA_BUILDS=")
+            if not line.startswith("EXTRA_BUILDS=")
             and not line.startswith("INTERNAL_CI=")
             and not line.startswith(_RESUME_NEXT_SCOPE_VAR + "=")
             and not line.startswith(_RESUME_NEXT_PACKAGE_VAR + "=")
@@ -613,9 +612,6 @@ def main():
     parser.add_argument("--extra-builds",
                         help="Comma-separated extra build namespaces to run after main steps "
                              "(e.g. guix or guix,gentoo,azl3).")
-    parser.add_argument("--build-guix-also",
-                        help=argparse.SUPPRESS,
-                        action="store_true")
     parser.add_argument("--no-create-config",
                         help="Do not automatically create config file",
                         action="store_true")
@@ -658,8 +654,6 @@ def main():
 
     args = parser.parse_args()
     args.extra_builds = parse_extra_builds(args.extra_builds)
-    if args.build_guix_also and "guix" not in args.extra_builds:
-        args.extra_builds.append("guix")
 
     # Mode validation
     def check_types():
@@ -786,7 +780,7 @@ def main():
                               repo_path=args.repo,
                               early_preseed=args.early_preseed,
                               mirrors=args.mirrors,
-                              build_guix_also=("guix" in args.extra_builds))
+                              extra_builds=args.extra_builds)
 
     bootstrap(args, generator, target, args.target_size, cleanup)
     cleanup()
diff --git a/steps-guix/manifest b/steps-guix/manifest
index 093f2af0..178eea56 100644
--- a/steps-guix/manifest
+++ b/steps-guix/manifest
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 #
-# Guix extension manifest. Runs after main /steps manifest when BUILD_GUIX_ALSO=True.
+# Guix extension manifest. Runs after main /steps manifest when EXTRA_BUILDS includes guix.
 
 # We need a 64-bit kernel to enable Guix to run 64-bit programs.
 # Build 64-bit kernel
diff --git a/steps/improve/after.sh b/steps/improve/after.sh
index 63fed6f7..38e7bf3e 100644
--- a/steps/improve/after.sh
+++ b/steps/improve/after.sh
@@ -18,10 +18,6 @@ if [ -d /steps/after ]; then
 fi
 
 extra_builds="${EXTRA_BUILDS:-}"
-# Backward compatibility for older bootstrap.cfg.
-if [ -z "${extra_builds}" ] && [ "${BUILD_GUIX_ALSO}" = True ]; then
-    extra_builds="guix"
-fi
 
 if [ -n "${extra_builds}" ]; then
     old_ifs="${IFS}"
diff --git a/steps/improve/make_bootable.sh b/steps/improve/make_bootable.sh
index de1c8de4..e12e5521 100644
--- a/steps/improve/make_bootable.sh
+++ b/steps/improve/make_bootable.sh
@@ -122,10 +122,6 @@ EOF
 cat >> /init <<- 'EOF'
 run_extra_builds_if_requested() {
     extra_builds="${EXTRA_BUILDS:-}"
-    # Backward compatibility for older bootstrap.cfg.
-    if [ -z "${extra_builds}" ] && [ "${BUILD_GUIX_ALSO}" = True ]; then
-        extra_builds="guix"
-    fi
     if [ -z "${extra_builds}" ]; then
         return 0
     fi