diff --git a/Lib/http/cookiejar.py b/Lib/http/cookiejar.py
index e3df007033b3cd..93b10d26c84545 100644
--- a/Lib/http/cookiejar.py
+++ b/Lib/http/cookiejar.py
@@ -640,7 +640,7 @@ def eff_request_host(request):
 
     """
     erhn = req_host = request_host(request)
-    if req_host.find(".") == -1 and not IPV4_RE.search(req_host):
+    if "." not in req_host:
         erhn = req_host + ".local"
     return req_host, erhn
 
diff --git a/Misc/NEWS.d/next/Library/2022-12-24-16-39-53.gh-issue-100519.G_dZLP.rst b/Misc/NEWS.d/next/Library/2022-12-24-16-39-53.gh-issue-100519.G_dZLP.rst
new file mode 100644
index 00000000000000..6b889b61c2744d
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-12-24-16-39-53.gh-issue-100519.G_dZLP.rst
@@ -0,0 +1,2 @@
+Small simplification of :func:`http.cookiejar.eff_request_host` that
+improves readability and better matches the RFC wording.