check for null-byte at argv[1][0]

1 files changed, 1 insertions, 1 deletions

diff --git a/simplebl.c b/simplebl.c
index b1fd622..f4d81ea 100644
--- a/simplebl.c
+++ b/simplebl.c
@@ -178,7 +178,7 @@ main(int argc, char *argv[])
 
 	val = strtonum(argv[2], 0, LONG_MAX/2);
 
-	if (argv[1][1])
+	if (!argv[1][0] || argv[1][1])
 		goto invalid_mode;
 	switch (argv[1][0]) {
 	case '-':