diff --git a/README.md b/README.md
index 14098f8..aaacc8a 100644
--- a/README.md
+++ b/README.md
@@ -5,12 +5,13 @@
 SHA3 Keccak Hashsum Tool - ALBANESE Lab (c) 2020-2021
 
 Usage of sha3sum:
-sha3sum [-v] [-b N] [-c <hash.ext>] -t <file.ext>
+sha3sum [-v] [-b N] [-c <hash.ext>] [-r] -t <file.ext>
 
   -b int
         Bits: 224, 256, 384 and 512. (default 224)
   -c string
         Check hashsum file.
+  -r    Process directories recursively.
   -t string
         Target file/wildcard to generate hashsum list.
   -v    Verbose mode. (The exit code is always 0 in this mode)