diff --git a/src/shrpx_connect_blocker.cc b/src/shrpx_connect_blocker.cc
index 03396ad8..164dea86 100644
--- a/src/shrpx_connect_blocker.cc
+++ b/src/shrpx_connect_blocker.cc
@@ -80,7 +80,8 @@ void ConnectBlocker::on_failure() {
 
   ++fail_count_;
 
-  auto base_backoff = pow(MULTIPLIER, std::min(MAX_BACKOFF_EXP, fail_count_));
+  auto base_backoff = pow(
+      MULTIPLIER, static_cast<double>(std::min(MAX_BACKOFF_EXP, fail_count_)));
   auto dist = std::uniform_real_distribution<>(-JITTER * base_backoff,
                                                JITTER * base_backoff);
 
diff --git a/src/shrpx_live_check.cc b/src/shrpx_live_check.cc
index 5f84a423..ba0d150d 100644
--- a/src/shrpx_live_check.cc
+++ b/src/shrpx_live_check.cc
@@ -157,7 +157,8 @@ constexpr auto JITTER = 0.2;
 } // namespace
 
 void LiveCheck::schedule() {
-  auto base_backoff = pow(MULTIPLIER, std::min(fail_count_, MAX_BACKOFF_EXP));
+  auto base_backoff = pow(
+      MULTIPLIER, static_cast<double>(std::min(fail_count_, MAX_BACKOFF_EXP)));
   auto dist = std::uniform_real_distribution<>(-JITTER * base_backoff,
                                                JITTER * base_backoff);