diff --git a/tests/server/sockfilt.c b/tests/server/sockfilt.c
index 34eb20b990c87e8721ecad8358a4563e530f7f4b..38015e22fbe772b72ab4e5b5e3f6ad3457325bda 100644
--- a/tests/server/sockfilt.c
+++ b/tests/server/sockfilt.c
@@ -1087,6 +1087,10 @@ int main(int argc, char *argv[])
 #ifdef WIN32
   win32_init();
   atexit(win32_cleanup);
+
+  setmode(fileno(stdin), O_BINARY);
+  setmode(fileno(stdout), O_BINARY);
+  setmode(fileno(stderr), O_BINARY);
 #endif
 
   install_signal_handlers();