diff --git a/man/irb.1 b/man/irb.1
index 63726f0a7a..6cc6d03231 100644
--- a/man/irb.1
+++ b/man/irb.1
@@ -40,7 +40,7 @@ Suppresses read of ~/.irbrc
 .It Fl m
 Bc mode (load mathn, fraction or matrix are available)
 .Pp
-.It Fl -r Ar load-module
+.It Fl r Ar load-module
 Same as `ruby -r'
 .Pp
 .It Fl I Ar path