diff --git a/src/ex_getln.c b/src/ex_getln.c
index b70755e..1512b03 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -5646,7 +5646,7 @@
  * Returns NUL when something is wrong.
  */
     int
-get_cmdline_type()
+get_cmdline_type(void)
 {
     struct cmdline_info *p = get_ccline_ptr();