diff --git a/lib/spack/spack/test/concretization/core.py b/lib/spack/spack/test/concretization/core.py
index d6f06dbbb9d..3b125cbbf34 100644
--- a/lib/spack/spack/test/concretization/core.py
+++ b/lib/spack/spack/test/concretization/core.py
@@ -1483,6 +1483,12 @@ def test_reuse_by_namespace(self, mutable_database, mock_packages):
         assert noreuse.installed
         assert noreuse.satisfies("@0.8.13")
 
+        # Expected behavior same as second concretization
+        spack.config.set("concretizer:reuse", {"namespaces": ["foobar"]})
+        noreuse = spack.concretize.concretize_one("libelf")
+        assert noreuse.installed
+        assert noreuse.satisfies("@0.8.13")
+
     def test_reuse_with_flags(self, mutable_database, mutable_config):
         spack.config.set("concretizer:reuse", True)
         spec = spack.concretize.concretize_one("pkg-a cflags=-g cxxflags=-g")