diff --git a/lib/net/ftp.rb b/lib/net/ftp.rb
index 3536e01ba3..bb746098df 100644
--- a/lib/net/ftp.rb
+++ b/lib/net/ftp.rb
@@ -1366,7 +1366,7 @@ module Net
     end
 
     #
-    # Returns +true+ iff the connection is closed.
+    # Returns +true+ if and only if the connection is closed.
     #
     def closed?
       @sock == nil or @sock.closed?