diff --git a/lib/spack/spack/cmd/develop.py b/lib/spack/spack/cmd/develop.py
index e46fde7a4ad..b3aee538c59 100644
--- a/lib/spack/spack/cmd/develop.py
+++ b/lib/spack/spack/cmd/develop.py
@@ -102,7 +102,7 @@ def assure_concrete_spec(env: spack.environment.Environment, spec: spack.spec.Sp
                     )
         else:
             # look up the maximum version so infintiy versions are preferred for develop
-            version = max(spec.package_class.versions.keys())
+            version = max(spack.repo.PATH.get_pkg_class(spec.fullname).versions.keys())
             tty.msg(f"Defaulting to highest version: {spec.name}@{version}")
     spec.versions = spack.version.VersionList([version])