diff --git a/cmd/common.go b/cmd/common.go
index df6fe3e..63eb46e 100644
--- a/cmd/common.go
+++ b/cmd/common.go
@@ -23,7 +23,7 @@ var numWorkers = flag.Int("num_workers", 2, "Number of concurrent matchers")
 var parallelFetch = flag.Int("parallel_fetch", 2, "Number of concurrent GetEntries fetches")
 var script = flag.String("script", "", "Script to execute when a matching certificate is found")
 var logsFilename = flag.String("logs", "", "JSON file containing log URLs")
-var underwater = flag.Bool("underwater", false, "Monitor certificates from distrusted CAs")
+var underwater = flag.Bool("underwater", false, "Monitor certificates from distrusted CAs instead of trusted CAs")
 var noSave = flag.Bool("no_save", false, "Do not save a copy of matching certificates")
 var verbose = flag.Bool("verbose", false, "Be verbose")
 var allTime = flag.Bool("all_time", false, "Scan certs from all time, not just since last scan")