--- origsrc/lib/freopen.c	2020-01-01 07:14:23.000000000 -0700
+++ src/lib/freopen.c	2022-04-16 22:41:38.090786400 -0600
@@ -59,6 +59,15 @@ rpl_freopen (const char *filename, const
   errno = 0;
 #endif
 
+#if __CYGWIN__
+  if (!filename && !strcmp (mode, "wb"))
+    {
+      int flag = fcntl (fileno (stream), F_GETFL);
+      if (0 <= flag && (flag & O_APPEND))
+        mode = "ab";
+    }
+
+#endif
   result = orig_freopen (filename, mode, stream);
 
   if (!result)