diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,7 @@
+# 0.1.1.1 (2021-09-10)
+
+- Optimise `insertWithIndex` function ([#10](https://github.com/klapaucius/vector-hashtables/pull/10)).
+
 # 0.1.1.0 (2021-09-10)
 
 - Add `alter` function to public interface ([#9](https://github.com/klapaucius/vector-hashtables/pull/9)).
diff --git a/src/Data/Vector/Hashtables/Internal.hs b/src/Data/Vector/Hashtables/Internal.hs
--- a/src/Data/Vector/Hashtables/Internal.hs
+++ b/src/Data/Vector/Hashtables/Internal.hs
@@ -328,17 +328,18 @@
 insertWithIndex
   :: (MVector ks k, MVector vs v, PrimMonad m, Hashable k, Eq k)
   => Int -> Int -> k -> v -> MutVar (PrimState m) (Dictionary_ (PrimState m) ks k vs v) -> Dictionary_ (PrimState m) ks k vs v -> Int -> m ()
-insertWithIndex !targetBucket !hashCode' key' value' getDRef d@Dictionary{..} i
-      | i >= 0 = do
-           hc <- hashCode ! i
-           if hc == hashCode'
-               then do
-                   k  <- key !~ i
-                   if k == key'
-                       then value <~~ i $ value'
-                       else insertWithIndex targetBucket hashCode' key' value' getDRef d =<< next ! i
-               else insertWithIndex targetBucket hashCode' key' value' getDRef d =<< next ! i
-      | otherwise = addOrResize targetBucket hashCode' key' value' getDRef d
+insertWithIndex !targetBucket !hashCode' key' value' getDRef d@Dictionary{..} = go where
+  go i
+    | i >= 0 = do
+         hc <- hashCode ! i
+         if hc == hashCode'
+             then do
+                 k  <- key !~ i
+                 if k == key'
+                     then value <~~ i $ value'
+                     else go =<< next ! i
+             else go =<< next ! i
+    | otherwise = addOrResize targetBucket hashCode' key' value' getDRef d
 {-# INLINE insertWithIndex #-}
 
 addOrResize
diff --git a/vector-hashtables.cabal b/vector-hashtables.cabal
--- a/vector-hashtables.cabal
+++ b/vector-hashtables.cabal
@@ -1,5 +1,5 @@
 name:                vector-hashtables
-version:             0.1.1.0
+version:             0.1.1.1
 synopsis:            Efficient vector-based mutable hashtables implementation.
 description:
   This package provides efficient vector-based hashtable implementation similar to .NET Generic Dictionary implementation (at the time of 2015).