diff --git a/ext/-test-/gvl/call_without_gvl/call_without_gvl.c b/ext/-test-/gvl/call_without_gvl/call_without_gvl.c
index 0ee64a24ac..f3071d5768 100644
--- a/ext/-test-/gvl/call_without_gvl/call_without_gvl.c
+++ b/ext/-test-/gvl/call_without_gvl/call_without_gvl.c
@@ -1,6 +1,5 @@
 #include "ruby/ruby.h"
 #include "ruby/thread.h"
-#include <sys/select.h>
 
 static void*
 native_sleep_callback(void *data)