diff --git a/test/13_subdir_package/bin/before_build.sh b/test/13_subdir_package/bin/before_build.sh
new file mode 100755
index 00000000..3f77a8c5
--- /dev/null
+++ b/test/13_subdir_package/bin/before_build.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo 'before_build.sh executed.'
diff --git a/test/13_subdir_package/cibuildwheel_test.py b/test/13_subdir_package/cibuildwheel_test.py
new file mode 100644
index 00000000..27dc5842
--- /dev/null
+++ b/test/13_subdir_package/cibuildwheel_test.py
@@ -0,0 +1,23 @@
+import os
+import platform
+
+import utils
+
+project_dir = os.path.dirname(__file__)
+
+
+def test():
+    package_dir = os.path.join(project_dir, 'src', 'spam')
+    # build the wheels
+    actual_wheels = utils.cibuildwheel_run(project_dir, package_dir=package_dir, add_env={
+        'CIBW_BEFORE_BUILD': '{project}/bin/before_build.sh',
+        'CIBW_TEST_COMMAND': 'python {package}/test/run_tests.py',
+        # this shouldn't depend on the version of python, so build only
+        # CPython 3.6
+        'CIBW_BUILD': 'cp36-*',
+    })
+
+    # check that the expected wheels are produced
+    expected_wheels = [w for w in utils.expected_wheels('spam', '0.1.0')
+                       if 'cp36' in w]
+    assert set(actual_wheels) == set(expected_wheels)
diff --git a/test/13_subdir_package/src/spam/setup.py b/test/13_subdir_package/src/spam/setup.py
new file mode 100644
index 00000000..637d7ff0
--- /dev/null
+++ b/test/13_subdir_package/src/spam/setup.py
@@ -0,0 +1,8 @@
+from setuptools import Extension, setup
+
+
+setup(
+    name="spam",
+    ext_modules=[Extension('spam', sources=['spam.c'])],
+    version="0.1.0",
+)
diff --git a/test/13_subdir_package/src/spam/spam.c b/test/13_subdir_package/src/spam/spam.c
new file mode 100644
index 00000000..d1ab0f22
--- /dev/null
+++ b/test/13_subdir_package/src/spam/spam.c
@@ -0,0 +1,48 @@
+#include <Python.h>
+
+static PyObject *
+spam_system(PyObject *self, PyObject *args)
+{
+    const char *command;
+    int sts;
+
+    if (!PyArg_ParseTuple(args, "s", &command))
+        return NULL;
+    sts = system(command);
+    return PyLong_FromLong(sts);
+}
+
+/* Module initialization */
+
+#if PY_MAJOR_VERSION >= 3
+    #define MOD_INIT(name) PyMODINIT_FUNC PyInit_##name(void)
+    #define MOD_DEF(m, name, doc, methods, module_state_size) \
+        static struct PyModuleDef moduledef = { \
+            PyModuleDef_HEAD_INIT, name, doc, module_state_size, methods, }; \
+        m = PyModule_Create(&moduledef);
+    #define MOD_RETURN(m) return m;
+#else
+    #define MOD_INIT(name) PyMODINIT_FUNC init##name(void)
+    #define MOD_DEF(m, name, doc, methods, module_state_size) \
+        m = Py_InitModule3(name, methods, doc);
+    #define MOD_RETURN(m) return;
+#endif
+
+static PyMethodDef module_methods[] = {
+    {"system", (PyCFunction)spam_system, METH_VARARGS, 
+     "Execute a shell command."},
+    {NULL}  /* Sentinel */
+};
+
+MOD_INIT(spam)
+{
+    PyObject* m;
+
+    MOD_DEF(m, 
+            "spam", 
+            "Example module", 
+            module_methods,
+            -1)
+
+    MOD_RETURN(m)
+}
diff --git a/test/13_subdir_package/src/spam/test/run_tests.py b/test/13_subdir_package/src/spam/test/run_tests.py
new file mode 100644
index 00000000..abaa183d
--- /dev/null
+++ b/test/13_subdir_package/src/spam/test/run_tests.py
@@ -0,0 +1 @@
+print('run_tests.py called!')
diff --git a/test/shared/utils.py b/test/shared/utils.py
index d1e1f0a1..609ab9d7 100644
--- a/test/shared/utils.py
+++ b/test/shared/utils.py
@@ -41,13 +41,15 @@ def cibuildwheel_get_build_identifiers(project_path, env=None):
     return cmd_output.strip().split('\n')
 
 
-def cibuildwheel_run(project_path, env=None, add_env=None, output_dir=None):
+def cibuildwheel_run(project_path, package_dir='.', env=None, add_env=None, output_dir=None):
     '''
     Runs cibuildwheel as a subprocess, building the project at project_path.
 
     Uses the current Python interpreter.
 
     :param project_path: path of the project to be built.
+    :param package_dir: path of the package to be built. Can be absolute, or
+    relative to project_path.
     :param env: full environment to be used, os.environ if None
     :param add_env: environment used to update env
     :param output_dir: directory where wheels are saved. If None, a temporary
@@ -64,7 +66,7 @@ def cibuildwheel_run(project_path, env=None, add_env=None, output_dir=None):
 
     with TemporaryDirectoryIfNone(output_dir) as _output_dir:
         subprocess.check_call(
-            [sys.executable, '-m', 'cibuildwheel', '--output-dir', str(_output_dir)],
+            [sys.executable, '-m', 'cibuildwheel', '--output-dir', str(_output_dir), package_dir],
             env=env,
             cwd=project_path,
         )