diff --git a/CMakeLists.txt b/CMakeLists.txt
index e020738453..a5ae3cd462 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -178,6 +178,7 @@ set(PYBIND11_HEADERS
     include/pybind11/operators.h
     include/pybind11/pybind11.h
     include/pybind11/pytypes.h
+    include/pybind11/smart_holder.h
     include/pybind11/stl.h
     include/pybind11/stl_bind.h
     include/pybind11/stl/filesystem.h
diff --git a/tests/extra_python_package/test_files.py b/tests/extra_python_package/test_files.py
index 8f7aec48ce..28a4bb2f49 100644
--- a/tests/extra_python_package/test_files.py
+++ b/tests/extra_python_package/test_files.py
@@ -44,11 +44,12 @@
     "include/pybind11/options.h",
     "include/pybind11/pybind11.h",
     "include/pybind11/pytypes.h",
+    "include/pybind11/smart_holder.h",
     "include/pybind11/stl.h",
     "include/pybind11/stl_bind.h",
+    "include/pybind11/trampoline_self_life_support.h",
     "include/pybind11/type_caster_pyobject_ptr.h",
     "include/pybind11/typing.h",
-    "include/pybind11/trampoline_self_life_support.h",
 }
 
 detail_headers = {