diff --git a/src/AsyncNameResolver.cc b/src/AsyncNameResolver.cc
index 8d4e2b23..09e85229 100644
--- a/src/AsyncNameResolver.cc
+++ b/src/AsyncNameResolver.cc
@@ -71,7 +71,7 @@ void callback(void* arg, int status, int timeouts, ares_addrinfo* result)
 }
 
 namespace {
-void sock_state_cb(void* arg, int fd, int read, int write)
+void sock_state_cb(void* arg, ares_socket_t fd, int read, int write)
 {
   auto resolver = static_cast<AsyncNameResolver*>(arg);
 
@@ -79,7 +79,7 @@ void sock_state_cb(void* arg, int fd, int read, int write)
 }
 } // namespace
 
-void AsyncNameResolver::handle_sock_state(int fd, int read, int write)
+void AsyncNameResolver::handle_sock_state(ares_socket_t fd, int read, int write)
 {
   int events = 0;
 
@@ -142,9 +142,9 @@ void AsyncNameResolver::resolve(const std::string& name)
   ares_getaddrinfo(channel_, name.c_str(), nullptr, &hints, callback, this);
 }
 
-int AsyncNameResolver::getFds(fd_set* rfdsPtr, fd_set* wfdsPtr) const
+ares_socket_t AsyncNameResolver::getFds(fd_set* rfdsPtr, fd_set* wfdsPtr) const
 {
-  auto nfds = 0;
+  ares_socket_t nfds = 0;
 
   for (const auto& ent : socks_) {
     if (ent.events & EventPoll::EVENT_READ) {
diff --git a/src/AsyncNameResolver.h b/src/AsyncNameResolver.h
index 065ef534..cc19260e 100644
--- a/src/AsyncNameResolver.h
+++ b/src/AsyncNameResolver.h
@@ -47,7 +47,7 @@
 namespace aria2 {
 
 struct AsyncNameResolverSocketEntry {
-  int fd;
+  ares_socket_t fd;
   int events;
 };
 
@@ -89,7 +89,7 @@ public:
 
   STATUS getStatus() const { return status_; }
 
-  int getFds(fd_set* rfdsPtr, fd_set* wfdsPtr) const;
+  ares_socket_t getFds(fd_set* rfdsPtr, fd_set* wfdsPtr) const;
 
   void process(fd_set* rfdsPtr, fd_set* wfdsPtr);
 
@@ -108,7 +108,7 @@ public:
 
   const std::string& getHostname() const { return hostname_; }
 
-  void handle_sock_state(int sock, int read, int write);
+  void handle_sock_state(ares_socket_t sock, int read, int write);
 };
 
 } // namespace aria2
diff --git a/src/SelectEventPoll.cc b/src/SelectEventPoll.cc
index d9397b20..42943ac0 100644
--- a/src/SelectEventPoll.cc
+++ b/src/SelectEventPoll.cc
@@ -129,8 +129,8 @@ SelectEventPoll::AsyncNameResolverEntry::AsyncNameResolverEntry(
 {
 }
 
-int SelectEventPoll::AsyncNameResolverEntry::getFds(fd_set* rfdsPtr,
-                                                    fd_set* wfdsPtr)
+ares_socket_t SelectEventPoll::AsyncNameResolverEntry::getFds(fd_set* rfdsPtr,
+                                                              fd_set* wfdsPtr)
 {
   return nameResolver_->getFds(rfdsPtr, wfdsPtr);
 }
@@ -184,7 +184,7 @@ void SelectEventPoll::poll(const struct timeval& tv)
 
   for (auto& i : nameResolverEntries_) {
     auto& entry = i.second;
-    int fd = entry.getFds(&rfds, &wfds);
+    auto fd = entry.getFds(&rfds, &wfds);
     // TODO force error if fd == 0
     if (fdmax_ < fd) {
       fdmax_ = fd;
diff --git a/src/SelectEventPoll.h b/src/SelectEventPoll.h
index c09f423f..bb7a2da2 100644
--- a/src/SelectEventPoll.h
+++ b/src/SelectEventPoll.h
@@ -142,7 +142,7 @@ private:
               command_ < entry.command_);
     }
 
-    int getFds(fd_set* rfdsPtr, fd_set* wfdsPtr);
+    ares_socket_t getFds(fd_set* rfdsPtr, fd_set* wfdsPtr);
 
     void process(fd_set* rfdsPtr, fd_set* wfdsPtr);
   };