diff --git a/src/lua/psl.lua b/src/lua/psl.lua
index 6ce88ba..bc2f888 100644
--- a/src/lua/psl.lua
+++ b/src/lua/psl.lua
@@ -1,3 +1,4 @@
+local cjson = require "cjson"
 local http = require "resty.http"
 
 local _M = {}
@@ -26,10 +27,11 @@ end
 local function load_psl()
     local cache = ngx.shared.jasima_cache
     local cached = cache:get("psl")
-    if cached then return cached end
+    if cached then return cjson.decode(cached) end
+    ngx.log(ngx.DEBUG, "Cache miss on public suffix list")
     local rules, err = fetch_psl()
     if rules then
-        cache:set("psl", rules, 86400 * 7)  -- 1 week
+        cache:set("psl", cjson.encode(rules), 86400 * 7)  -- 1 week
         return rules
     else
         ngx.log(ngx.ERR, err or "Unknown error loading PSL")