diff --git a/lib/spack/spack/schema/concretizer.py b/lib/spack/spack/schema/concretizer.py
index e628519d56f..30f73d7557d 100644
--- a/lib/spack/spack/schema/concretizer.py
+++ b/lib/spack/spack/schema/concretizer.py
@@ -15,6 +15,7 @@
         "additionalProperties": False,
         "properties": {
             "reuse": {"type": "boolean"},
+            "enable_node_namespace": {"type": "boolean"},
             "targets": {
                 "type": "object",
                 "properties": {