diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index f6c36cf..7f6568c 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -3117,6 +3117,7 @@
 	PyMem_DEL(array);
 }
 
+static
 int fsconvert_strdup(PyObject *o, char**out)
 {
 	PyObject *bytes;