diff --git a/src/fmacros.h b/src/fmacros.h
index a6cf3578c..c16f5e204 100644
--- a/src/fmacros.h
+++ b/src/fmacros.h
@@ -36,9 +36,13 @@
 #define _GNU_SOURCE
 #endif
 
-#if defined(__linux__) || defined(__OpenBSD__) || defined(__NetBSD__)
+#if defined(__linux__) || defined(__OpenBSD__)
 #define _XOPEN_SOURCE 700
-#else
+/*
+ * On NetBSD, _XOPEN_SOURCE undefines _NETBSD_SOURCE and
+ * thus hides inet_aton etc.
+ */
+#elif !defined(__NetBSD__)
 #define _XOPEN_SOURCE
 #endif