diff --git a/libguile/net_db.c b/libguile/net_db.c
index ed1c54317..82da282b4 100644
--- a/libguile/net_db.c
+++ b/libguile/net_db.c
@@ -70,9 +70,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
-/* Some systems do not declare this.  Some systems do declare it, as a
-   macro.  */
-#ifndef h_errno
+#if !defined (HAVE_H_ERRNO)
 extern int h_errno;
 #endif