Index: sys/sys/event.h
===================================================================
--- sys/sys/event.h
+++ sys/sys/event.h
@@ -49,6 +49,25 @@
 #define EVFILT_EMPTY		(-13)	/* empty send socket buf */
 #define EVFILT_SYSCOUNT		13
 
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
+#define EV_SET(kevp_, a, b, c, d, e, f) do {	\
+    *(kevp_) = (struct kevent){			\
+	.ident = (a),				\
+	.filter = (b),				\
+	.flags = (c),				\
+	.fflags = (d),				\
+	.data = (e),				\
+	.udata = (f),				\
+	.ext[0] = 0,				\
+	.ext[1] = 0,				\
+	.ext[2] = 0,				\
+	.ext[3] = 0,				\
+    };						\
+} while(0)
+#else /* Pre-C99 */
+/* The definition of the local variable kevp could possibly conflict
+ * with a user-defined value passed in parameters a-f.
+ */
 #define EV_SET(kevp_, a, b, c, d, e, f) do {	\
 	struct kevent *kevp = (kevp_);		\
 	(kevp)->ident = (a);			\
@@ -62,6 +81,7 @@
 	(kevp)->ext[2] = 0;			\
 	(kevp)->ext[3] = 0;			\
 } while(0)
+#endif
 
 struct kevent {
 	__uintptr_t	ident;		/* identifier for this event */