diff --git a/src/main.c b/src/main.c
index f8b4fa9..51cd2c7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1872,7 +1872,7 @@
 		{
 		    set_option_value((char_u *)"verbosefile", 0L,
 					     (char_u *)argv[0] + argv_idx, 0);
-		    argv_idx = STRLEN(argv[0]);
+		    argv_idx = (int)STRLEN(argv[0]);
 		}
 		break;