diff --git a/client/fdfs_download_file.c b/client/fdfs_download_file.c
index 7cf5f93..8f59c83 100644
--- a/client/fdfs_download_file.c
+++ b/client/fdfs_download_file.c
@@ -27,6 +27,10 @@ int main(int argc, char *argv[])
 	int64_t file_offset;
 	int64_t download_bytes;
 	
+	if(argc<0)
+	{
+		return NULL;
+	}
 	if (argc < 3)
 	{
 		printf("Usage: %s <config_file> <file_id> " \