diff --git a/Changelog.md b/Changelog.md
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,9 @@
 # Revision history for network-control
 
+## 0.1.4
+
+* Using Integer instead of Int in LRUCache.
+
 ## 0.1.3
 
 * Simplify `maybeOpenRxWindow` and improve docs
diff --git a/Network/Control/LRUCache.hs b/Network/Control/LRUCache.hs
--- a/Network/Control/LRUCache.hs
+++ b/Network/Control/LRUCache.hs
@@ -14,7 +14,7 @@
 import Data.OrdPSQ (OrdPSQ)
 import qualified Data.OrdPSQ as PSQ
 
-type Priority = Int
+type Priority = Integer
 
 -- | Sized cache based on least recently used.
 data LRUCache k v = LRUCache
diff --git a/network-control.cabal b/network-control.cabal
--- a/network-control.cabal
+++ b/network-control.cabal
@@ -1,6 +1,6 @@
 cabal-version:   3.0
 name:            network-control
-version:         0.1.3
+version:         0.1.4
 license:         BSD-3-Clause
 license-file:    LICENSE
 maintainer:      kazu@iij.ad.jp
diff --git a/test/Network/Control/FlowSpec.hs b/test/Network/Control/FlowSpec.hs
--- a/test/Network/Control/FlowSpec.hs
+++ b/test/Network/Control/FlowSpec.hs
@@ -89,7 +89,7 @@
             [ -- Take a prefix (starting with the same initialFlow)
               Trace initialFlow <$> init (inits steps)
             , -- Take a suffix (starting with a later initialFlow)
-              map shiftInitialFlow $ tail (tails steps)
+              map shiftInitialFlow $ drop 1 (tails steps)
             ]
       where
         shiftInitialFlow :: [(Int, Step OpWithResult, RxFlow)] -> Trace