diff --git a/config.h.in b/config.h.in
index 2521fd327f..507e95acc3 100644
--- a/config.h.in
+++ b/config.h.in
@@ -31,6 +31,12 @@
 /* Define cpu-machine-OS */
 #undef OS
 
+/* Number of arguments your gethostbyaddr_r() function accepts */
+#undef GETHOSTBYADDR_R_NARGS
+
+/* Number of arguments your gethostbyname_r() function accepts */
+#undef GETHOSTBYNAME_R_NARGS
+
 /* The number of bytes in a long double.  */
 #undef SIZEOF_LONG_DOUBLE