diff --git a/src/screen.c b/src/screen.c
index 2e8a6aa..4c3c2b5 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -379,7 +379,7 @@
  * Return the index in ScreenLines[] for the current screen line.
  */
     int
-screen_get_current_line_off()
+screen_get_current_line_off(void)
 {
     return (int)(current_ScreenLine - ScreenLines);
 }
@@ -3962,7 +3962,7 @@
  * or inside a mapping.
  */
     int
-skip_showmode()
+skip_showmode(void)
 {
     // Call char_avail() only when we are going to show something, because it
     // takes a bit of time.  redrawing() may also call char_avail().