diff --git a/src/eval.c b/src/eval.c
index 4423419..ef25a3f 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -9387,8 +9387,7 @@
 }
 
     char_u *
-typval_tostring(arg)
-    typval_T	*arg;
+typval_tostring(typval_T *arg)
 {
     char_u	*tofree;
     char_u	numbuf[NUMBUFLEN];