diff --git a/Changelog.md b/Changelog.md
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,9 @@
 # Revision history for network-control
 
+## 0.1.7
+
+* Implementing setLRUCapacity.
+
 ## 0.1.6
 
 * Allowing size 0.
diff --git a/Network/Control/LRUCache.hs b/Network/Control/LRUCache.hs
--- a/Network/Control/LRUCache.hs
+++ b/Network/Control/LRUCache.hs
@@ -14,6 +14,7 @@
     newLRUCacheRef,
     cached,
     cached',
+    setLRUCapacity,
 
     -- * Internal
     empty',
@@ -120,17 +121,16 @@
 
 ----------------------------------------------------------------
 
+-- | Mutable LRUCache.
 newtype LRUCacheRef k v = LRUCacheRef (IORef (LRUCache k v))
 
+-- | Creating 'LRUCacheRef'.
 newLRUCacheRef :: Int -> IO (LRUCacheRef k v)
 newLRUCacheRef capacity = LRUCacheRef <$> newIORef (empty capacity)
 
-cached' :: Ord k => LRUCacheRef k v -> k -> IO (Maybe v)
-cached' (LRUCacheRef ref) k = do
-    atomicModifyIORef' ref $ \c -> case lookup' k c of
-        Nothing -> (c, Nothing)
-        Just (v, c') -> (c', Just v)
-
+-- | Looking up a target and adjusting the LRU cache.
+--   If not found, a new value is inserted.
+--   A pair of value and "found" is returned.
 cached :: Ord k => LRUCacheRef k v -> k -> IO v -> IO (v, Bool)
 cached (LRUCacheRef ref) k io = do
     lookupRes <- atomicModifyIORef' ref $ \c -> case lookup' k c of
@@ -142,3 +142,15 @@
             v <- io
             atomicModifyIORef' ref $ \c -> (insert k v c, ())
             return (v, False)
+
+-- | Looking up a target and adjusting the LRU cache.
+cached' :: Ord k => LRUCacheRef k v -> k -> IO (Maybe v)
+cached' (LRUCacheRef ref) k = do
+    atomicModifyIORef' ref $ \c -> case lookup' k c of
+        Nothing -> (c, Nothing)
+        Just (v, c') -> (c', Just v)
+
+-- | Setting capacity of the LRU cache.
+setLRUCapacity :: LRUCacheRef k v -> Int -> IO ()
+setLRUCapacity (LRUCacheRef ref) lim = atomicModifyIORef' ref $ \c ->
+    (c{lcLimit = lim}, ())
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:         0.1.6
+version:         0.1.7
 license:         BSD-3-Clause
 license-file:    LICENSE
 maintainer:      kazu@iij.ad.jp