diff --git a/macros.pyproject b/macros.pyproject
index 9ddd652..6e558b2 100644
--- a/macros.pyproject
+++ b/macros.pyproject
@@ -17,7 +17,7 @@ if [ -d %{buildroot}%{python3_sitearch} ]; then
 fi
 }
 
-%pyproject_buildrequires(r) %{expand:\\\
+%pyproject_buildrequires(rx:) %{expand:\\\
 echo 'python3-devel'
 echo 'python3dist(packaging)'
 echo 'python3dist(pip) >= 19'
diff --git a/pyproject_buildrequires.py b/pyproject_buildrequires.py
index a6ebc57..2a3fa63 100644
--- a/pyproject_buildrequires.py
+++ b/pyproject_buildrequires.py
@@ -42,7 +42,7 @@ def hook_call():
 
 class Requirements:
     """Requirement printer"""
-    def __init__(self, freeze_output):
+    def __init__(self, freeze_output, extras=''):
         self.installed_packages = {}
         for line in freeze_output.splitlines():
             line = line.strip()
@@ -51,6 +51,8 @@ class Requirements:
             name, version = line.split('==')
             self.installed_packages[name.strip()] = Version(version)
 
+        self.marker_env = {'extra': extras}
+
         self.missing_requirements = False
 
     def add(self, requirement_str, *, source=None):
@@ -68,7 +70,7 @@ class Requirements:
 
         name = canonicalize_name(requirement.name)
         if (requirement.marker is not None
-            and not requirement.marker.evaluate(environment={'extra': ''})
+            and not requirement.marker.evaluate(environment=self.marker_env)
         ):
             print_err(f'Ignoring alien requirement:', requirement_str)
             return
@@ -181,8 +183,10 @@ def python3dist(name, op=None, version=None):
         return f'python3dist({name}) {op} {version}'
 
 
-def generate_requires(freeze_output, *, include_runtime=False, toxenv=None):
-    requirements = Requirements(freeze_output)
+def generate_requires(
+    freeze_output, *, include_runtime=False, toxenv=None, extras='',
+):
+    requirements = Requirements(freeze_output, extras=extras)
 
     try:
         backend = get_backend(requirements)
@@ -206,6 +210,11 @@ def main(argv):
         help='generate test tequirements from tox environment '
             + '(not implemented; implies --runtime)',
     )
+    parser.add_argument(
+        '-x', '--extras', metavar='EXTRAS', default='',
+        help='comma separated list of "extras" for runtime requirements '
+            + '(e.g. -x testing,feature-x)',
+    )
 
     args = parser.parse_args(argv)
     if args.toxenv:
@@ -224,7 +233,11 @@ def main(argv):
     ).stdout
 
     try:
-        generate_requires(freeze_output, include_runtime=args.runtime)
+        generate_requires(
+            freeze_output,
+            include_runtime=args.runtime,
+            extras=args.extras,
+        )
     except Exception as e:
         # Log the traceback explicitly (it's useful debug info)
         traceback.print_exc()
diff --git a/test_pyproject_buildrequires.py b/test_pyproject_buildrequires.py
index 225d1c3..b6462b4 100644
--- a/test_pyproject_buildrequires.py
+++ b/test_pyproject_buildrequires.py
@@ -29,6 +29,7 @@ def test_data(case_name, capsys, tmp_path, monkeypatch):
         generate_requires(
             case['freeze_output'],
             include_runtime=case.get('include_runtime', False),
+            extras=case.get('extras', ''),
         )
     except SystemExit as e:
         assert e.code == case['result']
diff --git a/testcases.yaml b/testcases.yaml
index 77cc782..956e78e 100644
--- a/testcases.yaml
+++ b/testcases.yaml
@@ -142,13 +142,13 @@ Default build system, run dependencies in setup.py:
     python3dist(inst2) < 3
   result: 0
 
-Run dependencies with extras:
+Run dependencies with extras (not selected):
   freeze_output: |
     setuptools==50
     wheel==1
     pyyaml==1
   include_runtime: true
-  setup.py: |
+  setup.py: &pytest_setup_py |
         # slightly abriged copy of pytest's setup.py
         from setuptools import setup
 
@@ -198,3 +198,29 @@ Run dependencies with extras:
     python3dist(pluggy) >= 0.11
     python3dist(more-itertools) >= 4
   result: 0
+
+Run dependencies with extras (selected):
+  freeze_output: |
+    setuptools==50
+    wheel==1
+    pyyaml==1
+  include_runtime: true
+  extras: testing
+  setup.py: *pytest_setup_py
+  expected: |
+    python3dist(setuptools) >= 40.8
+    python3dist(wheel)
+    python3dist(wheel)
+    python3dist(setuptools) >= 40
+    python3dist(py) >= 1.5
+    python3dist(six) >= 1.10
+    python3dist(setuptools)
+    python3dist(attrs) >= 17.4
+    python3dist(atomicwrites) >= 1
+    python3dist(pluggy) >= 0.11
+    python3dist(more-itertools) >= 4
+    python3dist(argcomplete)
+    python3dist(hypothesis) >= 3.56
+    python3dist(nose)
+    python3dist(requests)
+  result: 0
diff --git a/tests/python-pytest.spec b/tests/python-pytest.spec
index e427ccf..d6ad7ab 100644
--- a/tests/python-pytest.spec
+++ b/tests/python-pytest.spec
@@ -27,7 +27,7 @@ py.test provides simple, yet powerful testing for Python.
 
 
 %generate_buildrequires
-%pyproject_buildrequires -r
+%pyproject_buildrequires -r -x testing
 
 
 %build
@@ -37,6 +37,12 @@ py.test provides simple, yet powerful testing for Python.
 %install
 %pyproject_install
 
+%check
+# Only run one test (which uses a test-only dependency, hypothesis).
+# (Unfortunately, some other tests still fail.)
+export PYTHONPATH=%{buildroot}%{python3_sitelib}
+%{__python3} -m pytest -k metafunc
+
 
 %files -n python3-%{pypi_name}
 %doc README.rst