1 files changed, 4 insertions, 2 deletions
diff --git a/libxcb/src/xcb_conn.c b/libxcb/src/xcb_conn.c
index 4a8f63bcf..0b080d4d4 100644
--- a/libxcb/src/xcb_conn.c
+++ b/libxcb/src/xcb_conn.c
@@ -78,8 +78,10 @@ size_t writev(int fildes, const struct iovec *iov, int iovcnt)
         errno =WSAGetLastError();
         if(errno == WSAEWOULDBLOCK)
           errno = EAGAIN;
-        assert(sum == 0);
-        return r;
+        if (sum)
+          return sum;
+        else
+          return r;
       }
       p += r;
       l -= r;