diff --git a/build-packages.py b/build-packages.py
index d19d949..328cb61 100644
--- a/build-packages.py
+++ b/build-packages.py
@@ -3,15 +3,44 @@ import subprocess
 import os
 import shutil
 import glob
+import sys
+
+LOCAL_REPO = "/tmp/pkgout"
+
+def repo_init():
+    os.makedirs(LOCAL_REPO, exist_ok=True)
+    conf_path = "/etc/pacman.conf"
+    with open(conf_path) as f:
+        conf = f.read()
+    if "[antergos-local]" not in conf:
+        with open(conf_path, "w") as f:
+            f.write(conf.replace(
+                "[core]",
+                "[antergos-local]\nSigLevel = Never\nServer = file:///tmp/pkgout\n\n[core]"
+            ))
+
+def repo_add(pkg_path):
+    db = f"{LOCAL_REPO}/antergos-local.db.tar.gz"
+    subprocess.run(["repo-add", db, pkg_path], capture_output=True)
+
+def repo_has(pkgname):
+    db = f"{LOCAL_REPO}/antergos-local.db.tar.gz"
+    if not os.path.exists(db):
+        return False
+    result = subprocess.run(
+        ["bsdtar", "-tf", db],
+        capture_output=True, text=True
+    )
+    return pkgname in result.stdout
 
 with open("packages.yaml") as f:
     pkgs = yaml.safe_load(f)["packages"]
 
-os.makedirs("/tmp/pkgout", exist_ok=True)
+repo_init()
 
 for pkg in pkgs:
     local_pkgbuild = f"packages/{pkg}/PKGBUILD"
-    build_dir = f"/tmp/{pkg}"
+    build_dir = f"/tmp/build-{pkg}"
 
     if os.path.exists(build_dir):
         shutil.rmtree(build_dir)
@@ -22,8 +51,22 @@ for pkg in pkgs:
         subprocess.run(["git", "clone", f"https://aur.archlinux.org/{pkg}.git", build_dir])
 
     subprocess.run(["chown", "-R", "builder:builder", build_dir])
-    subprocess.run(["su", "-", "builder", "-c", f"cd {build_dir} && makepkg -s --noconfirm --noprogress --skippgpcheck --skipinteg"])
 
-    subprocess.run(f"cp {build_dir}/*.pkg.tar.zst /tmp/pkgout/ || true", shell=True)
+    # Sync pacman so makepkg -s can resolve local packages
+    subprocess.run(["pacman", "-Sy", "--noconfirm"], capture_output=True)
+
+    result = subprocess.run(
+        ["su", "-", "builder", "-c", f"cd {build_dir} && makepkg -s --noconfirm --noprogress --skippgpcheck --skipinteg"],
+        capture_output=True, text=True
+    )
+    if result.returncode != 0:
+        print(f"::error::BUILD FAILED: {pkg}")
+        print(result.stdout[-500:])
+        print(result.stderr[-500:])
+        sys.exit(1)
+
+    for pkg_file in glob.glob(f"{build_dir}/*.pkg.tar.zst"):
+        shutil.copy(pkg_file, LOCAL_REPO)
+        repo_add(pkg_file)
 
 print("Done!")