diff --git a/Validity.md b/Validity.md
index b8f1566..316c96d 100644
--- a/Validity.md
+++ b/Validity.md
@@ -5,7 +5,7 @@ And some of the CAs supported this feature. (The Letsencrypt CA doesn't support
 There are 2 command options to use:
 
 1. The `--valid-to <date time>` option, which is for `NotAfter` field.
-2. The `--valid-from <date time>` option, which is for `NotBeofre` field.
+2. The `--valid-from <date time>` option, which is for `NotBefore` field.