diff --git a/scrapy/core/downloader/handlers/_httpx.py b/scrapy/core/downloader/handlers/_httpx.py
index da39e1bbc..fa712d119 100644
--- a/scrapy/core/downloader/handlers/_httpx.py
+++ b/scrapy/core/downloader/handlers/_httpx.py
@@ -95,8 +95,12 @@ class HttpxDownloadHandler(_Base):
             # hard limit on simultaneous connections (None for no limit, which
             # is what a CONCURRENT_CONNECTIONS_PER_HANDLER of 0 means)
             max_connections=self._pool_size_total or None,
-            # total number of idle connections in the pool (extra ones are closed)
-            max_keepalive_connections=self._pool_size_total or None,
+            # total number of idle connections in the pool (extra ones are
+            # closed); keeping none of them is how keepalive gets disabled,
+            # since expiry alone is subject to the resolution of the clock
+            max_keepalive_connections=(
+                (self._pool_size_total or None) if self._keepalive_timeout else 0
+            ),
             keepalive_expiry=self._keepalive_timeout,
         )