diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index d8bc6466bf6..bb69b191421 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -294,7 +294,7 @@ extern void dump_counts(FILE*);
 /* Flush stdout and stderr */
 
 void
-flush_std_files()
+flush_std_files(void)
 {
 	PyObject *fout = PySys_GetObject("stdout");
 	PyObject *ferr = PySys_GetObject("stderr");