Index: unix/tclUnixSock.c
===================================================================
--- unix/tclUnixSock.c
+++ unix/tclUnixSock.c
@@ -66,10 +66,11 @@
     struct addrinfo *myaddrlist; /* local address                  */
     struct addrinfo *myaddr;	 /* iterator over myaddrlist       */
     int filehandlers;	/* Caches FileHandlers that get set up while
                          * an async socket is not yet connected   */
     int status;         /* Cache status of async socket */
+    int cachedBlocking; /* Cache blocking mode of async socket */
 };
 
 /*
  * These bits may be ORed together into the "flags" field of a TcpState
  * structure.
@@ -345,10 +346,14 @@
 
     if (mode == TCL_MODE_BLOCKING) {
 	CLEAR_BITS(statePtr->flags, TCP_ASYNC_SOCKET);
     } else {
 	SET_BITS(statePtr->flags, TCP_ASYNC_SOCKET);
+    }
+    if (statePtr->flags & TCP_ASYNC_CONNECT) {
+        statePtr->cachedBlocking = mode;
+        return 0;
     }
     if (TclUnixSetBlockingMode(statePtr->fds.fd, mode) < 0) {
 	return errno;
     }
     return 0;
@@ -1036,11 +1041,11 @@
         /*
          * An asynchonous connection has finally succeeded or failed.
          */
         CLEAR_BITS(state->flags, TCP_ASYNC_CONNECT);
         TcpWatchProc(state, state->filehandlers);
-        TclUnixSetBlockingMode(state->fds.fd, TCL_MODE_BLOCKING);
+        TclUnixSetBlockingMode(state->fds.fd, state->cachedBlocking);
 
         /*
          * We need to forward the writable event that brought us here, bcasue
          * upon reading of getsockopt(SO_ERROR), at least some OSes clear the
          * writable state from the socket, and so a subsequent select() on
@@ -1120,10 +1125,11 @@
      * Allocate a new TcpState for this socket.
      */
     state = ckalloc(sizeof(TcpState));
     memset(state, 0, sizeof(TcpState));
     state->flags = async ? TCP_ASYNC_CONNECT : 0;
+    state->cachedBlocking = TCL_MODE_BLOCKING;
     state->addrlist = addrlist;
     state->myaddrlist = myaddrlist;
     state->fds.fd = -1;
 
     /*

