diff --git a/tests/test_buffers.cpp b/tests/test_buffers.cpp
index 3eb7df9464..ac4489f70c 100644
--- a/tests/test_buffers.cpp
+++ b/tests/test_buffers.cpp
@@ -389,6 +389,7 @@ TEST_SUBMODULE(buffers, m) {
     m.def("get_buffer_info", [](const py::buffer &buffer) { return buffer.request(); });
 
     // Expose Py_buffer for testing.
+    m.attr("PyBUF_FORMAT") = PyBUF_FORMAT;
     m.attr("PyBUF_SIMPLE") = PyBUF_SIMPLE;
     m.attr("PyBUF_ND") = PyBUF_ND;
     m.attr("PyBUF_STRIDES") = PyBUF_STRIDES;
diff --git a/tests/test_buffers.py b/tests/test_buffers.py
index 60565875a5..2612edb270 100644
--- a/tests/test_buffers.py
+++ b/tests/test_buffers.py
@@ -251,6 +251,16 @@ def test_c_contiguous_to_pybuffer(type):
         raise ValueError(f"Unknown parametrization {type}")
 
     info = m.get_py_buffer(mat, m.PyBUF_SIMPLE)
+    assert info.format is None
+    assert info.itemsize == ctypes.sizeof(ctypes.c_float)
+    assert info.len == 5 * 4 * info.itemsize
+    assert info.ndim == 0  # See discussion on PR #5407.
+    assert info.shape is None
+    assert info.strides is None
+    assert info.suboffsets is None
+    assert not info.readonly
+    info = m.get_py_buffer(mat, m.PyBUF_SIMPLE | m.PyBUF_FORMAT)
+    assert info.format == "f"
     assert info.itemsize == ctypes.sizeof(ctypes.c_float)
     assert info.len == 5 * 4 * info.itemsize
     assert info.ndim == 0  # See discussion on PR #5407.