diff --git a/lib/spack/spack/repo.py b/lib/spack/spack/repo.py
index 5290f23532e..e4a945f0bfe 100644
--- a/lib/spack/spack/repo.py
+++ b/lib/spack/spack/repo.py
@@ -1179,9 +1179,8 @@ def all_package_paths(self) -> Generator[str, None, None]:
             yield self.package_path(name)
 
     def packages_with_tags(self, *tags: str) -> Set[str]:
-        v = set(self.tag_index[tags[0].lower()])
-        for tag in tags[1:]:
-            v.intersection_update(self.tag_index[tag.lower()])
+        v = set(self.all_package_names())
+        v.intersection_update(*(self.tag_index[tag.lower()] for tag in tags))
         return v
 
     def all_package_classes(self) -> Generator[Type["spack.package_base.PackageBase"], None, None]: