diff --git a/INSTALLATION.md b/INSTALLATION.md
index 1245d4d..ba4962f 100644
--- a/INSTALLATION.md
+++ b/INSTALLATION.md
@@ -11,7 +11,7 @@ NOTE: Use either HCAPTCHA_ or RECAPTHCA_, not both.
 - POW_COOKIE_SECRET - different random string, a salt for pow cookies
 - HMAC_COOKIE_SECRET - different random string, a salt for pow cookies
 - RAY_ID - string to identify the HAProxy node by
-- BUCKET_DURATION - how long between bucket changes, invalidating cookies
+- CHALLENGE_EXPIRY - how long solution cookies last for, in seconds
 - CHALLENGE_INCLUDES_IP - any value, whether to lock solved challenges to IP or tor circuit
 - BACKEND_NAME - Optional, name of backend to build from hosts.map
 - SERVER_PREFIX - Optional, prefix of server names used in server-template
diff --git a/docker-compose.yml b/docker-compose.yml
index 4508446..86edc5c 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -31,7 +31,7 @@ services:
       - POW_COOKIE_SECRET=changeme
       - HMAC_COOKIE_SECRET=changeme
       - RAY_ID=docker
-      - BUCKET_DURATION=43200
+      - CHALLENGE_EXPIRY=43200
       - BACKEND_NAME=servers
       - SERVER_PREFIX=websrv
       - CHALLENGE_INCLUDES_IP=1
diff --git a/haproxy/template/trace.txt b/haproxy/template/trace.txt
index be55d08..48410ef 100644
--- a/haproxy/template/trace.txt
+++ b/haproxy/template/trace.txt
@@ -7,4 +7,4 @@ tls=%[ssl_fc]
 tlsv=%sslv
 sni=%[ssl_fc_sni]
 vey_id=%[env(RAY_ID)]
-bucket=%[env(BUCKET_DURATION)]
+expiry=%[env(CHALLENGE_EXPIRY)]
diff --git a/src/lua/libs/utils.lua b/src/lua/libs/utils.lua
index 1160c7b..eea98ff 100644
--- a/src/lua/libs/utils.lua
+++ b/src/lua/libs/utils.lua
@@ -1,7 +1,7 @@
 local _M = {}
 
 local sha = require("sha")
-local bucket_duration = tonumber(os.getenv("BUCKET_DURATION"))
+local challenge_expiry = tonumber(os.getenv("CHALLENGE_EXPIRY"))
 local challenge_includes_ip = os.getenv("CHALLENGE_INCLUDES_IP")
 local tor_control_port_password = os.getenv("TOR_CONTROL_PORT_PASSWORD")
 
@@ -26,7 +26,7 @@ function _M.generate_challenge(context, salt, user_key, is_applet)
 
 	local challenge_hash = sha.sha3_256(salt .. ip .. user_key .. user_agent)
 
-	local expiry = core.now()['sec'] + bucket_duration
+	local expiry = core.now()['sec'] + challenge_expiry
 
 	return challenge_hash, expiry