diff --git a/include/event2/util.h b/include/event2/util.h
index 126a3037..2b23e62b 100644
--- a/include/event2/util.h
+++ b/include/event2/util.h
@@ -256,6 +256,7 @@ ev_int64_t evutil_strtoll(const char *s, char **endptr, int base);
 #ifdef _EVENT_HAVE_GETTIMEOFDAY
 #define evutil_gettimeofday(tv, tz) gettimeofday((tv), (tz))
 #else
+struct timezone;
 int evutil_gettimeofday(struct timeval *tv, struct timezone *tz);
 #endif