diff --git a/crates/throttle/src/throttle.rs b/crates/throttle/src/throttle.rs
index eab53631..25e9da7c 100644
--- a/crates/throttle/src/throttle.rs
+++ b/crates/throttle/src/throttle.rs
@@ -60,7 +60,7 @@ else
   throttled = 0
   reset_after = math.ceil(new_tat - now)
   retry_after = 0
-  redis.call("SET", key, new_tat, "PX", reset_after)
+  redis.call("SET", key, new_tat, "EX", reset_after)
 end
 
 return {throttled, remaining, reset_after, retry_after, tostring(diff), tostring(interval)}
diff --git a/docs/changelog/main.md b/docs/changelog/main.md
index b2f13995..5b451427 100644
--- a/docs/changelog/main.md
+++ b/docs/changelog/main.md
@@ -112,3 +112,5 @@
 * Rebuilding a MIME message (such as via `msg:check_fix_conformance`) that had
   binary attachments would incorrectly re-interpret the bytes as windows-1252
   encoded characters, damaging the attachment.
+* Using redis-based throttles without redis-cell and with long periods (eg: `500/d`)
+  could result in throttles being exceeded.