diff --git a/include/pybind11/detail/class.h b/include/pybind11/detail/class.h
index 1ed2e90c2c..60e7b3e516 100644
--- a/include/pybind11/detail/class.h
+++ b/include/pybind11/detail/class.h
@@ -497,8 +497,6 @@ extern "C" inline void pybind11_object_dealloc(PyObject *self) {
     Py_DECREF(type);
 }
 
-std::string error_string();
-
 /** Create the type which can be used as a common base for all classes.  This is
     needed in order to satisfy Python's requirements for multiple inheritance.
     Return value: New reference. */
diff --git a/include/pybind11/gil.h b/include/pybind11/gil.h
index 888810493c..8fe29a225f 100644
--- a/include/pybind11/gil.h
+++ b/include/pybind11/gil.h
@@ -21,9 +21,6 @@ PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
-// forward declarations
-PyThreadState *get_thread_state_unchecked();
-
 PYBIND11_NAMESPACE_END(detail)
 
 #if !defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)