diff --git a/src/msw/sockmsw.cpp b/src/msw/sockmsw.cpp
index 1edcf8d67d..6bae719a94 100644
--- a/src/msw/sockmsw.cpp
+++ b/src/msw/sockmsw.cpp
@@ -634,7 +634,7 @@ int wxSocketImplMSW::Write(const void *buffer, int size)
   }
 
   /* If the socket is blocking, wait for writability (with a timeout) */
-  if ( BlockForOutputWithTimeout() )
+  if ( !BlockForOutputWithTimeout() )
     return -1;
 
   /* Write the data */