diff --git a/src/agents.nim b/src/agents.nim
index 63a7677..a907e7b 100644
--- a/src/agents.nim
+++ b/src/agents.nim
@@ -31,7 +31,7 @@ proc windows(): string =
     trident = ["", "; Trident/5.0", "; Trident/6.0", "; Trident/7.0"]
   "Windows " & sample(nt) & sample(enc) & sample(arch) & sample(trident)
 
-let macs = toSeq(6..15).mapIt($it) & @["14_4", "10_1", "9_3"]
+const macs = toSeq(6..15).mapIt($it) & @["14_4", "10_1", "9_3"]
 
 proc mac(): string =
   "Macintosh; Intel Mac OS X 10_" & sample(macs) & sample(enc)
diff --git a/src/redis_cache.nim b/src/redis_cache.nim
index b434def..66ef415 100644
--- a/src/redis_cache.nim
+++ b/src/redis_cache.nim
@@ -4,11 +4,12 @@ import redis, redpool, flatty, supersnappy
 
 import types, api
 
-const redisNil = "\0\0"
+const
+  redisNil = "\0\0"
+  baseCacheTime = 60 * 60
 
 var
   pool {.threadvar.}: RedisPool
-  baseCacheTime = 60 * 60
   rssCacheTime: int
   listCacheTime*: int
 
diff --git a/src/utils.nim b/src/utils.nim
index e92d220..2ca0617 100644
--- a/src/utils.nim
+++ b/src/utils.nim
@@ -9,8 +9,6 @@ var
 const
   https* = "https://"
   twimg* = "pbs.twimg.com/"
-  badJpgExts = @["1500x500", "jpgn", "jpg:", "jpg_", "_jpg"]
-  badPngExts = @["pngn", "png:", "png_", "_png"]
   twitterDomains = @[
     "twitter.com",
     "pic.twitter.com",
@@ -19,6 +17,7 @@ const
     "pbs.twimg.com",
     "video.twimg.com"
   ]
+  nitterParams = ["name", "tab", "id", "list", "referer", "scroll"]
 
 proc setHmacKey*(key: string) =
   hmacKey = key
@@ -43,18 +42,9 @@ proc getPicUrl*(link: string): string =
   else:
     &"/pic/{encodeUrl(link)}"
 
-proc cleanFilename*(filename: string): string =
-  const reg = re"[^A-Za-z0-9._-]"
-  result = filename.replace(reg, "_")
-  if badJpgExts.anyIt(it in result):
-    result &= ".jpg"
-  elif badPngExts.anyIt(it in result):
-    result &= ".png"
-
 proc filterParams*(params: Table): seq[(string, string)] =
-  const filter = ["name", "tab", "id", "list", "referer", "scroll"]
   for p in params.pairs():
-    if p[1].len > 0 and p[0] notin filter:
+    if p[1].len > 0 and p[0] notin nitterParams:
       result.add p
 
 proc isTwitterUrl*(uri: Uri): bool =