diff --git a/README.rst b/README.rst
index 7f3afac..ad85364 100644
--- a/README.rst
+++ b/README.rst
@@ -155,7 +155,7 @@ module.
     --remove-internal-links PRESERVE_INTERNAL_LINKS
                           Remove links that start with a '#' like anchors.
     --exclude-pseudoclasses
-                          Pseudo classes like p:last-child', p:first-child, etc
+                          Pseudo classes like p:last-child', p:first-child, :nth-child, etc
     --preserve-style-tags
                           Do not delete <style></style> tags from the html
                           document.
diff --git a/premailer/__main__.py b/premailer/__main__.py
index 11c4bbd..7d32dfb 100644
--- a/premailer/__main__.py
+++ b/premailer/__main__.py
@@ -50,7 +50,7 @@ def main(args):
     parser.add_argument(
         "--exclude-pseudoclasses",
         default=False,
-        help="Pseudo classes like p:last-child', p:first-child, etc",
+        help="Pseudo classes like p:last-child', p:first-child, :nth-child, etc",
         action="store_true",
         dest="exclude_pseudoclasses",
     )