diff --git a/attic/_chunker.c b/attic/_chunker.c
index 5492e8e55..392fab4f6 100644
--- a/attic/_chunker.c
+++ b/attic/_chunker.c
@@ -141,7 +141,7 @@ chunker_fill(Chunker *c)
     return 1;
 }
 
-PyObject *
+static PyObject *
 PyBuffer_FromMemory(void *data, Py_ssize_t len)
 {
     Py_buffer buffer;