Use HAVE_SNPRINTF, not HAVE_SPRINTF, for checking the availability of
snprintf.
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 863a407..d33e190 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -2420,7 +2420,7 @@
 	n = PyArg_ParseTuple(sa, "si|ii", &hostp, &port, &flowinfo, scope_id);
 	if (n == 0)
 		goto fail;
-#ifdef HAVE_SPRINTF
+#ifdef HAVE_SNPRINTF
 	snprintf(pbuf, sizeof(pbuf), "%d", port);
 #else
 	sprintf(pbuf, "%d", port);