diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 72fb9594dc..e09540b3e8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1124,7 +1124,7 @@ jobs:
         uses: jwlawson/actions-setup-cmake@v2.0
 
       - name: Install ninja-build tool
-        uses: seanmiddleditch/gha-setup-ninja@v5
+        uses: seanmiddleditch/gha-setup-ninja@v6
 
       - name: Run pip installs
         run: |
diff --git a/include/pybind11/detail/class.h b/include/pybind11/detail/class.h
index f501467ded..1ed2e90c2c 100644
--- a/include/pybind11/detail/class.h
+++ b/include/pybind11/detail/class.h
@@ -574,9 +574,9 @@ extern "C" inline int pybind11_clear(PyObject *self) {
 inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
     auto *type = &heap_type->ht_type;
     type->tp_flags |= Py_TPFLAGS_HAVE_GC;
-#if PY_VERSION_HEX < 0x030B0000
-    type->tp_dictoffset = type->tp_basicsize;           // place dict at the end
-    type->tp_basicsize += (ssize_t) sizeof(PyObject *); // and allocate enough space for it
+#if PY_VERSION_HEX < 0x030B0000 || defined(PYPY_VERSION) // For PyPy see PR #5508
+    type->tp_dictoffset = type->tp_basicsize;            // place dict at the end
+    type->tp_basicsize += (ssize_t) sizeof(PyObject *);  // and allocate enough space for it
 #else
     type->tp_flags |= Py_TPFLAGS_MANAGED_DICT;
 #endif