diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index 99f2ca5a8bd..0e60e94d7de 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -849,6 +849,8 @@ def on_model(model):
             error_handler = ErrorHandler(best_model)
             error_handler.raise_if_errors()
 
+            # build specs from spec attributes in the model
+            spec_attrs = [(name, tuple(rest)) for name, *rest in extract_args(best_model, "attr")]
             answers = builder.build_specs(spec_attrs)
 
             # add best spec to the results