diff --git a/conf.py b/conf.py
index 3cbb2bf..3d27b70 100644
--- a/conf.py
+++ b/conf.py
@@ -306,7 +306,8 @@ def setup(app):
 #texinfo_no_detailmenu = False
 
 rst_epilog = """
-.. _PSR-7: http://www.php-fig.org/psr/psr-7
+.. _PSR-7: https://www.php-fig.org/psr/psr-7
+.. _PSR-18: https://www.php-fig.org/psr/psr-18
 .. _Composer: https://getcomposer.org
 .. _HttplugBundle: https://github.com/php-http/HttplugBundle
 """
diff --git a/discovery.rst b/discovery.rst
index 56ac2d4..de50b4f 100644
--- a/discovery.rst
+++ b/discovery.rst
@@ -291,4 +291,3 @@ and that it is not used by the Discovery Service by default. It is simply
 provided as a convenient option when writing tests.
 
 .. _PSR-17: http://www.php-fig.org/psr/psr-17
-.. _PSR-18: http://www.php-fig.org/psr/psr-18