diff --git a/lib/spack/spack/test/concretize.py b/lib/spack/spack/test/concretize.py
index 76af2168ff5..4e7c18e5c4b 100644
--- a/lib/spack/spack/test/concretize.py
+++ b/lib/spack/spack/test/concretize.py
@@ -1138,36 +1138,31 @@ def test_external_package_versions(self, spec_str, is_external, expected):
         assert s.satisfies(expected)
 
     def test_reuse_does_not_overwrite_root_dev_specs(
-            self, tmpdir, mock_packages, install_mockery, mock_fetch):
+            self, mock_packages, install_mockery, mock_fetch):
         # potential parameters
         package_name = 'dev-build-test-install'
-        package_version = '0.0.0'
-        spec_str = package_name
-        dev_spec_str = '%s@%s dev_path=/fake' % (package_name,
-                                                 package_version)
+        dev_spec_str = '%s dev_path=/fake' % package_name
         # concretize and install a non-dev version
-        s = Spec(spec_str).concretized()
+        s = Spec(package_name).concretized()
         s.package.do_install(fake=True)
         # concretize a dev version
-        dev_spec = Spec(dev_spec_str).concretized(reuse=True)
-        assert dev_spec.dag_hash() is not s.dag_hash()
+        with spack.config.override("concretizer:reuse", True):
+            dev_spec = Spec(dev_spec_str).concretized()
+        assert dev_spec.dag_hash() != s.dag_hash()
 
     def test_reuse_does_not_overwrite_dependent_dev_specs(
-            self, tmpdir, mock_packages, install_mockery, mock_fetch):
+            self, mock_packages, install_mockery, mock_fetch):
         # potential parameters
         root_spec = 'dev-build-test-dependent'
-        package_name = 'dev-build-test-install'
-        package_version = '0.0.0'
-
-        spec_str = root_spec
-        dev_spec_str = '%s ^%s@%s dev_path=/fake' % (root_spec, package_name,
-                                                     package_version)
+        dependency_spec = 'dev-build-test-install'
+        dev_spec_str = '%s ^%s dev_path=/fake' % (root_spec, dependency_spec)
         # concretize and install a non-dev version
-        s = Spec(spec_str).concretized()
+        s = Spec(root_spec).concretized()
         s.package.do_install(fake=True)
         # concretize a dev version
-        dev_spec = Spec(dev_spec_str).concretized(reuse=True)
-        assert dev_spec.dag_hash() is not s.dag_hash()
+        with spack.config.override("concretizer:reuse", True):
+            dev_spec = Spec(dev_spec_str).concretized()
+        assert dev_spec.dag_hash() != s.dag_hash()
 
     @pytest.mark.regression('20292')
     @pytest.mark.parametrize('context', [