diff --git a/doc/sphinxext/redirect_from.py b/doc/sphinxext/redirect_from.py
index 7a7e6aa9cdc8..37b56373a3bf 100644
--- a/doc/sphinxext/redirect_from.py
+++ b/doc/sphinxext/redirect_from.py
@@ -33,7 +33,7 @@
 """
 
 from pathlib import Path
-from docutils.parsers.rst import Directive
+from sphinx.util.docutils import SphinxDirective
 from sphinx.domains import Domain
 from sphinx.util import logging
 
@@ -51,9 +51,9 @@
 
 
 def setup(app):
-    RedirectFrom.app = app
     app.add_directive("redirect-from", RedirectFrom)
     app.add_domain(RedirectFromDomain)
+    app.connect("builder-inited", _clear_redirects)
     app.connect("build-finished", _generate_redirects)
 
     metadata = {'parallel_read_safe': True}
@@ -73,8 +73,8 @@ def redirects(self):
         """The mapping of the redirects."""
         return self.data.setdefault('redirects', {})
 
-    def clear_doc(self, docnames):
-        self.redirects.clear()
+    def clear_doc(self, docname):
+        self.redirects.pop(docname, None)
 
     def merge_domaindata(self, docnames, otherdata):
         for src, dst in otherdata['redirects'].items():
@@ -86,15 +86,14 @@ def merge_domaindata(self, docnames, otherdata):
                     f"{self.redirects[src]} and {otherdata['redirects'][src]}")
 
 
-class RedirectFrom(Directive):
+class RedirectFrom(SphinxDirective):
     required_arguments = 1
 
     def run(self):
         redirected_doc, = self.arguments
-        env = self.app.env
-        domain = env.get_domain('redirect_from')
-        current_doc = env.path2doc(self.state.document.current_source)
-        redirected_reldoc, _ = env.relfn2path(redirected_doc, current_doc)
+        domain = self.env.get_domain('redirect_from')
+        current_doc = self.env.path2doc(self.state.document.current_source)
+        redirected_reldoc, _ = self.env.relfn2path(redirected_doc, current_doc)
         if redirected_reldoc in domain.redirects:
             raise ValueError(
                 f"{redirected_reldoc} is already noted as redirecting to "
@@ -119,3 +118,10 @@ def _generate_redirects(app, exception):
             logger.info('making refresh html file: %s redirect to %s', k, v)
             p.parent.mkdir(parents=True, exist_ok=True)
             p.write_text(html, encoding='utf-8')
+
+
+def _clear_redirects(app):
+    domain = app.env.get_domain('redirect_from')
+    if domain.redirects:
+        logger.info('clearing cached redirects')
+        domain.redirects.clear()