diff --git a/Include/pylifecycle.h b/Include/pylifecycle.h
index c5368b3c5edaa0..783fcb455eb528 100644
--- a/Include/pylifecycle.h
+++ b/Include/pylifecycle.h
@@ -32,6 +32,8 @@ PyAPI_FUNC(void) _Py_NO_RETURN Py_Exit(int);
 /* Bootstrap __main__ (defined in Modules/main.c) */
 PyAPI_FUNC(int) Py_Main(int argc, wchar_t **argv);
 
+PyAPI_FUNC(int) Py_FrozenMain(int argc, char **argv);
+
 PyAPI_FUNC(int) Py_BytesMain(int argc, char **argv);
 
 /* In pathconfig.c */
diff --git a/Misc/NEWS.d/next/C API/2020-12-10-10-43-03.bpo-42591.CXNY8G.rst b/Misc/NEWS.d/next/C API/2020-12-10-10-43-03.bpo-42591.CXNY8G.rst
new file mode 100644
index 00000000000000..3519859f7be89d
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-12-10-10-43-03.bpo-42591.CXNY8G.rst	
@@ -0,0 +1,3 @@
+Export the :c:func:`Py_FrozenMain` function: fix a Python 3.9.0 regression.
+Python 3.9 uses ``-fvisibility=hidden`` and the function was not exported
+explicitly and so not exported.