diff --git a/src/charset.c b/src/charset.c
index d8feb4e..826a768 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1764,7 +1764,7 @@
  * columns (bytes) at the start of a given line
  */
     int
-getwhitecols_curline()
+getwhitecols_curline(void)
 {
     return getwhitecols(ml_get_curline());
 }