diff --git a/src/compat.h b/src/compat.h
--- a/src/compat.h
+++ b/src/compat.h
@@ -86,7 +86,7 @@
 size_t strnlen(const char *start, size_t max_len);
 #endif // HAVE_DECL_STRNLEN
 
-static bool inline IsSelectableSocket(SOCKET s) {
+static bool inline IsSelectableSocket(const SOCKET &s) {
 #ifdef WIN32
     return true;
 #else
diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2277,6 +2277,7 @@
 
     // Set to non-blocking, incoming connections will also inherit this
     if (!SetSocketNonBlocking(hListenSocket, true)) {
+        CloseSocket(hListenSocket);
         strError = strprintf("BindListenPort: Setting listening socket to "
                              "non-blocking failed, error %s\n",
                              NetworkErrorString(WSAGetLastError()));
diff --git a/src/netbase.h b/src/netbase.h
--- a/src/netbase.h
+++ b/src/netbase.h
@@ -64,9 +64,9 @@
 /** Close socket and set hSocket to INVALID_SOCKET */
 bool CloseSocket(SOCKET &hSocket);
 /** Disable or enable blocking-mode for a socket */
-bool SetSocketNonBlocking(SOCKET &hSocket, bool fNonBlocking);
+bool SetSocketNonBlocking(const SOCKET &hSocket, bool fNonBlocking);
 /** Set the TCP_NODELAY flag on a socket */
-bool SetSocketNoDelay(SOCKET &hSocket);
+bool SetSocketNoDelay(const SOCKET &hSocket);
 /**
  * Convert milliseconds to a struct timeval for e.g. select.
  */
diff --git a/src/netbase.cpp b/src/netbase.cpp
--- a/src/netbase.cpp
+++ b/src/netbase.cpp
@@ -200,7 +200,7 @@
  * @note This function requires that hSocket is in non-blocking mode.
  */
 static IntrRecvError InterruptibleRecv(char *data, size_t len, int timeout,
-                                       SOCKET &hSocket) {
+                                       const SOCKET &hSocket) {
     int64_t curTime = GetTimeMillis();
     int64_t endTime = curTime + timeout;
     // Maximum time to wait in one select call. It will take up until this time
@@ -464,10 +464,12 @@
     SetSocketNoDelay(hSocket);
 
     // Set to non-blocking
-    if (!SetSocketNonBlocking(hSocket, true))
+    if (!SetSocketNonBlocking(hSocket, true)) {
+        CloseSocket(hSocket);
         return error("ConnectSocketDirectly: Setting socket to non-blocking "
                      "failed, error %s\n",
                      NetworkErrorString(WSAGetLastError()));
+    }
 
     if (connect(hSocket, (struct sockaddr *)&sockaddr, len) == SOCKET_ERROR) {
         int nErr = WSAGetLastError();
@@ -675,7 +677,7 @@
     return ret != SOCKET_ERROR;
 }
 
-bool SetSocketNonBlocking(SOCKET &hSocket, bool fNonBlocking) {
+bool SetSocketNonBlocking(const SOCKET &hSocket, bool fNonBlocking) {
     if (fNonBlocking) {
 #ifdef WIN32
         u_long nOne = 1;
@@ -684,7 +686,6 @@
         int fFlags = fcntl(hSocket, F_GETFL, 0);
         if (fcntl(hSocket, F_SETFL, fFlags | O_NONBLOCK) == SOCKET_ERROR) {
 #endif
-            CloseSocket(hSocket);
             return false;
         }
     } else {
@@ -695,7 +696,6 @@
         int fFlags = fcntl(hSocket, F_GETFL, 0);
         if (fcntl(hSocket, F_SETFL, fFlags & ~O_NONBLOCK) == SOCKET_ERROR) {
 #endif
-            CloseSocket(hSocket);
             return false;
         }
     }
@@ -703,7 +703,7 @@
     return true;
 }
 
-bool SetSocketNoDelay(SOCKET &hSocket) {
+bool SetSocketNoDelay(const SOCKET &hSocket) {
     int set = 1;
     int rc = setsockopt(hSocket, IPPROTO_TCP, TCP_NODELAY, (const char *)&set,
                         sizeof(int));