diff --git a/Modules/_struct.c b/Modules/_struct.c
index 9c45dbe..e567627 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -182,6 +182,8 @@
 
 /* Same, but handling unsigned long */
 
+#ifndef PY_STRUCT_OVERFLOW_MASKING
+
 static int
 get_ulong(PyObject *v, unsigned long *p)
 {
@@ -202,6 +204,8 @@
 	return 0;
 }
 
+#endif /* PY_STRUCT_OVERFLOW_MASKING */
+
 #ifdef HAVE_LONG_LONG
 
 /* Same, but handling native long long. */