diff --git a/tests/functional/test_install_config.py b/tests/functional/test_install_config.py
index 62c88be1f6c..712fc4ae5c7 100644
--- a/tests/functional/test_install_config.py
+++ b/tests/functional/test_install_config.py
@@ -7,6 +7,7 @@
 from tests.lib.server import file_response, package_page
 
 
+@pytest.mark.fails_on_new_resolver
 def test_options_from_env_vars(script):
     """
     Test if ConfigOptionParser reads env vars (e.g. not using PyPI here)
@@ -15,9 +16,10 @@ def test_options_from_env_vars(script):
     script.environ['PIP_NO_INDEX'] = '1'
     result = script.pip('install', '-vvv', 'INITools', expect_error=True)
     assert "Ignoring indexes:" in result.stdout, str(result)
-
-    err = "distributionnotfound: no matching distribution found for initools"
-    assert err in result.stdout.lower()
+    assert (
+        "DistributionNotFound: No matching distribution found for INITools"
+        in result.stdout
+    )
 
 
 def test_command_line_options_override_env_vars(script, virtualenv):
@@ -42,6 +44,7 @@ def test_command_line_options_override_env_vars(script, virtualenv):
 
 
 @pytest.mark.network
+@pytest.mark.fails_on_new_resolver
 def test_env_vars_override_config_file(script, virtualenv):
     """
     Test that environmental variables override settings in config files.
@@ -65,7 +68,7 @@ def test_env_vars_override_config_file(script, virtualenv):
     script.environ['PIP_NO_INDEX'] = '0'
     virtualenv.clear()
     result = script.pip('install', '-vvv', 'INITools')
-    assert "successfully installed initools" in result.stdout.lower()
+    assert "Successfully installed INITools" in result.stdout
 
 
 @pytest.mark.network
@@ -173,6 +176,7 @@ def test_config_file_override_stack(
     assert requests[3]["PATH_INFO"] == "/files/INITools-0.2.tar.gz"
 
 
+@pytest.mark.fails_on_new_resolver
 def test_options_from_venv_config(script, virtualenv):
     """
     Test if ConfigOptionParser reads a virtualenv-local config file
@@ -185,8 +189,10 @@ def test_options_from_venv_config(script, virtualenv):
         f.write(conf)
     result = script.pip('install', '-vvv', 'INITools', expect_error=True)
     assert "Ignoring indexes:" in result.stdout, str(result)
-    err = "distributionnotfound: no matching distribution found for initools"
-    assert err in result.stdout.lower()
+    assert (
+        "DistributionNotFound: No matching distribution found for INITools"
+        in result.stdout
+    )
 
 
 def test_install_no_binary_via_config_disables_cached_wheels(