diff --git a/src/dht.cpp b/src/dht.cpp
index d5305fd9..ee74d39b 100644
--- a/src/dht.cpp
+++ b/src/dht.cpp
@@ -29,51 +29,10 @@ extern "C" {
 #include <gnutls/gnutls.h>
 }
 
-#ifndef _WIN32
-#include <arpa/inet.h>
-#else
-#include <ws2tcpip.h>
-#endif
-
 #include <algorithm>
 #include <random>
 #include <sstream>
 
-#ifndef _WIN32
-#include <unistd.h>
-#else
-#include <io.h>
-#endif
-
-#include <fcntl.h>
-#include <cstring>
-
-#ifdef _WIN32
-
-static bool
-set_nonblocking(int fd, int nonblocking)
-{
-    unsigned long mode = !!nonblocking;
-    int rc = ioctlsocket(fd, FIONBIO, &mode);
-    return rc == 0;
-}
-
-extern const char *inet_ntop(int, const void *, char *, socklen_t);
-
-#else
-
-static bool
-set_nonblocking(int fd, int nonblocking)
-{
-    int rc = fcntl(fd, F_GETFL, 0);
-    if (rc < 0)
-        return false;
-    rc = fcntl(fd, F_SETFL, nonblocking?(rc | O_NONBLOCK):(rc & ~O_NONBLOCK));
-    return rc >= 0;
-}
-
-#endif
-
 namespace dht {
 
 using namespace std::placeholders;
@@ -1841,18 +1800,10 @@ Dht::Dht(int s, int s6, Config config)
     scheduler.syncTime();
     if (s < 0 && s6 < 0)
         return;
-
-    if (s >= 0) {
+    if (s >= 0)
         buckets4 = {Bucket {AF_INET}};
-        if (!set_nonblocking(s, 1))
-            throw DhtException("Can't set socket to non-blocking mode");
-    }
-
-    if (s6 >= 0) {
+    if (s6 >= 0)
         buckets6 = {Bucket {AF_INET6}};
-        if (!set_nonblocking(s6, 1))
-            throw DhtException("Can't set socket to non-blocking mode");
-    }
 
     search_id = std::uniform_int_distribution<decltype(search_id)>{}(rd);
 
diff --git a/src/network_engine.cpp b/src/network_engine.cpp
index f4b22a7a..56b821f2 100644
--- a/src/network_engine.cpp
+++ b/src/network_engine.cpp
@@ -25,6 +25,17 @@
 
 #include <msgpack.hpp>
 
+#ifndef _WIN32
+#include <arpa/inet.h>
+#include <unistd.h>
+#else
+#include <ws2tcpip.h>
+#include <io.h>
+#endif
+#include <fcntl.h>
+
+#include <cstring>
+
 namespace dht {
 namespace net {
 
@@ -58,6 +69,32 @@ static const uint8_t v4prefix[16] = {
 
 constexpr unsigned SEND_NODES {8};
 
+#ifdef _WIN32
+
+static bool
+set_nonblocking(int fd, int nonblocking)
+{
+    unsigned long mode = !!nonblocking;
+    int rc = ioctlsocket(fd, FIONBIO, &mode);
+    return rc == 0;
+}
+
+extern const char *inet_ntop(int, const void *, char *, socklen_t);
+
+#else
+
+static bool
+set_nonblocking(int fd, int nonblocking)
+{
+    int rc = fcntl(fd, F_GETFL, 0);
+    if (rc < 0)
+        return false;
+    rc = fcntl(fd, F_SETFL, nonblocking?(rc | O_NONBLOCK):(rc & ~O_NONBLOCK));
+    return rc >= 0;
+}
+
+#endif
+
 enum class MessageType {
     Error = 0,
     Reply,
@@ -151,6 +188,14 @@ NetworkEngine::NetworkEngine(InfoHash& myid, NetId net, int s, int s6, Logger& l
     onGetValues(onGetValues), onListen(onListen), onAnnounce(onAnnounce), onRefresh(onRefresh), myid(myid),
     network(net), dht_socket(s), dht_socket6(s6), DHT_LOG(log), scheduler(scheduler)
 {
+    if (dht_socket >= 0) {
+        if (!set_nonblocking(dht_socket, 1))
+            throw DhtException("Can't set socket to non-blocking mode");
+    }
+    if (dht_socket6 >= 0) {
+        if (!set_nonblocking(dht_socket6, 1))
+            throw DhtException("Can't set socket to non-blocking mode");
+    }
     transaction_id = std::uniform_int_distribution<decltype(transaction_id)>{1}(rd_device);
 }