Index: src/OFIPSocketAsyncConnector.m
==================================================================
--- src/OFIPSocketAsyncConnector.m
+++ src/OFIPSocketAsyncConnector.m
@@ -171,11 +171,15 @@
 	[_socket setCanBlock: false];
 #endif
 
 	if (![_socket of_connectSocketToAddress: &address errNo: &errNo]) {
 #if !defined(OF_NINTENDO_3DS) && !defined(OF_WII)
+# ifdef OF_WINDOWS
+		if (errNo == EINPROGRESS || errNo == EWOULDBLOCK) {
+# else
 		if (errNo == EINPROGRESS) {
+# endif
 			[OFRunLoop of_addAsyncConnectForSocket: _socket
 							  mode: runLoopMode
 						      delegate: self];
 			return;
 		} else {

Index: src/OFSPXSocket.m
==================================================================
--- src/OFSPXSocket.m
+++ src/OFSPXSocket.m
@@ -115,11 +115,15 @@
 	}
 
 	_socket.canBlock = false;
 
 	if (![_socket of_connectSocketToAddress: &address errNo: &errNo]) {
+#ifdef OF_WINDOWS
+		if (errNo == EINPROGRESS || errNo == EWOULDBLOCK) {
+#else
 		if (errNo == EINPROGRESS) {
+#endif
 			[OFRunLoop of_addAsyncConnectForSocket: _socket
 							  mode: runLoopMode
 						      delegate: self];
 			return;
 		}

Index: src/OFSPXStreamSocket.m
==================================================================
--- src/OFSPXStreamSocket.m
+++ src/OFSPXStreamSocket.m
@@ -116,11 +116,15 @@
 	}
 
 	_socket.canBlock = false;
 
 	if (![_socket of_connectSocketToAddress: &address errNo: &errNo]) {
+#ifdef OF_WINDOWS
+		if (errNo == EINPROGRESS || errNo == EWOULDBLOCK) {
+#else
 		if (errNo == EINPROGRESS) {
+#endif
 			[OFRunLoop of_addAsyncConnectForSocket: _socket
 							  mode: runLoopMode
 						      delegate: self];
 			return;
 		}