diff --git a/src/shrpx_dns_resolver.cc b/src/shrpx_dns_resolver.cc
index 32dfc0a6..d7c77ebd 100644
--- a/src/shrpx_dns_resolver.cc
+++ b/src/shrpx_dns_resolver.cc
@@ -216,7 +216,9 @@ void DNSResolver::reset_timeout() {
   if (tv == nullptr) {
     return;
   }
-  timer_.repeat = tv->tv_sec + tv->tv_usec / 1000000.;
+  // To avoid that timer_.repeat becomes 0, which makes ev_timer_again
+  // useless, add tiny fraction of time.
+  timer_.repeat = tv->tv_sec + tv->tv_usec / 1000000. + 1e-9;
   ev_timer_again(loop_, &timer_);
 }