diff --git a/Data/HashMap/Array.hs b/Data/HashMap/Array.hs
index 06eca773..55161b4c 100644
--- a/Data/HashMap/Array.hs
+++ b/Data/HashMap/Array.hs
@@ -321,7 +321,7 @@ updateWith' ary idx f = update ary idx $! f (index ary idx)
 -- inserting it into the array.
 updateWithInternal' :: Array e -> Int -> (e -> (Int, e)) -> RunResA e
 updateWithInternal' ary idx f =
-    let (!sz, !e) = f (index ary idx)
+    let !(!sz, !e) = f (index ary idx)
     in RunRes sz (update ary idx e)
 {-# INLINE updateWithInternal' #-}
 
diff --git a/Data/HashMap/Base.hs b/Data/HashMap/Base.hs
index 20c079c8..4e84e966 100644
--- a/Data/HashMap/Base.hs
+++ b/Data/HashMap/Base.hs
@@ -529,7 +529,7 @@ insertInternal k0 v0 m0 = go h0 k0 v0 0 m0
             in (1, bitmapIndexedOrFull (b .|. m) ary')
         | otherwise =
             let !st  = A.index ary i
-                (!sz, !st') = go h k x (s+bitsPerSubkey) st
+                !(!sz, !st') = go h k x (s+bitsPerSubkey) st
             in if st' `ptrEq` st
                then (sz, t)
                else (sz, BitmapIndexed b (A.update ary i st'))
@@ -537,7 +537,7 @@ insertInternal k0 v0 m0 = go h0 k0 v0 0 m0
             i = sparseIndex b m
     go h k x s t@(Full ary) =
         let !st  = A.index ary i
-            (!sz, !st') = go h k x (s+bitsPerSubkey) st
+            !(!sz, !st') = go h k x (s+bitsPerSubkey) st
         in if st' `ptrEq` st
             then (sz, t)
             else (sz, Full (update16 ary i st'))
@@ -755,8 +755,8 @@ deleteInternal k0 m0 = go h0 k0 0 m0
         | b .&. m == 0 = (0, t)
         | otherwise =
             let !st = A.index ary i
-                (!sz, !st') = go h k (s+bitsPerSubkey) st
-            in (sz,) (if st' `ptrEq` st
+                !(!sz, !st') = go h k (s+bitsPerSubkey) st
+            in (sz,) $! if st' `ptrEq` st
                 then t
                 else case st' of
                 Empty | A.length ary == 1 -> Empty
@@ -769,28 +769,28 @@ deleteInternal k0 m0 = go h0 k0 0 m0
                     where
                       bIndexed = BitmapIndexed (b .&. complement m) (A.delete ary i)
                 l | isLeafOrCollision l && A.length ary == 1 -> l
-                _ -> BitmapIndexed b (A.update ary i st'))
+                _ -> BitmapIndexed b (A.update ary i st')
       where m = mask h s
             i = sparseIndex b m
     go h k s t@(Full ary) =
         let !st   = A.index ary i
-            (!sz, !st') = go h k (s+bitsPerSubkey) st
-        in (sz,) (if st' `ptrEq` st
+            !(!sz, !st') = go h k (s+bitsPerSubkey) st
+        in (sz,) $! if st' `ptrEq` st
             then t
             else case st' of
             Empty ->
                 let ary' = A.delete ary i
                     bm   = fullNodeMask .&. complement (1 `unsafeShiftL` i)
                 in BitmapIndexed bm ary'
-            _ -> Full (A.update ary i st'))
+            _ -> Full (A.update ary i st')
       where i = index h s
     go h k _ t@(Collision hy v)
         | h == hy = case indexOf k v of
             Just i
                 | A.length v == 2 ->
-                    (-1,) (if i == 0
+                    (-1,) $!if i == 0
                     then Leaf h (A.index v 1)
-                    else Leaf h (A.index v 0))
+                    else Leaf h (A.index v 0)
                 | otherwise -> (-1, Collision h (A.delete v i))
             Nothing -> (0, t)
         | otherwise = (0, t)
@@ -1010,7 +1010,7 @@ unionWithKeyInternal f hm1 (HashMap siz hm2) = go 0 siz hm1 hm2
     leafHashCode _ = error "leafHashCode"
 
     goDifferentHash sz s h1 h2 t1 t2
-        | m1 == m2  = let (!dsz, !hm) = go sz (s+bitsPerSubkey) t1 t2
+        | m1 == m2  = let !(!dsz, !hm) = go sz (s+bitsPerSubkey) t1 t2
                       in (dsz, BitmapIndexed m1 (A.singleton hm))
         | m1 <  m2  = (sz, BitmapIndexed (m1 .|. m2) (A.pair t1 t2))
         | otherwise = (sz, BitmapIndexed (m1 .|. m2) (A.pair t2 t1))
@@ -1066,7 +1066,7 @@ unionArrayByInternal siz f b1 b2 ary1 ary2 = A.runInternal $ do
             | m > b'        = return sz
             | b' .&. m == 0 = go sz i i1 i2 (m `unsafeShiftL` 1)
             | ba .&. m /= 0 = do
-                let (!dsz, !hm) = f sz (A.index ary1 i1) (A.index ary2 i2)
+                let !(!dsz, !hm) = f sz (A.index ary1 i1) (A.index ary2 i2)
                 A.write mary i hm
                 go dsz (i+1) (i1+1) (i2+1) (m `unsafeShiftL` 1)
             | b1 .&. m /= 0 = do
@@ -1317,9 +1317,9 @@ filterMapAuxInternal onLeaf onColl = go 0
                       _                       -> (siz,) . BitmapIndexed b <$> trim mary 1
                 _ -> do
                     ary2 <- trim mary j
-                    return $! (siz,) (if j == maxChildren
-                                      then Full ary2
-                                      else BitmapIndexed b ary2)
+                    return . (siz,) $! if j == maxChildren
+                                       then Full ary2
+                                       else BitmapIndexed b ary2
             | bi .&. b == 0 = step ary mary b i j (bi `unsafeShiftL` 1) n sz
             | otherwise = case go sz (A.index ary i) of
                 (dsz, Empty) -> step ary mary (b .&. complement bi) (i+1) j
diff --git a/Data/HashMap/Strict.hs b/Data/HashMap/Strict.hs
index f76079e3..68b9fa63 100644
--- a/Data/HashMap/Strict.hs
+++ b/Data/HashMap/Strict.hs
@@ -443,7 +443,7 @@ unionWithKeyInternal f hm1 (HashMap siz hm2) = go 0 siz hm1 hm2
     leafHashCode _ = error "leafHashCode"
 
     goDifferentHash sz s h1 h2 t1 t2
-        | m1 == m2  = let (!dsz, !hm) = go sz (s+bitsPerSubkey) t1 t2
+        | m1 == m2  = let !(!dsz, !hm) = go sz (s+bitsPerSubkey) t1 t2
                       in (dsz, BitmapIndexed m1 (A.singleton hm))
         | m1 <  m2  = (sz, BitmapIndexed (m1 .|. m2) (A.pair t1 t2))
         | otherwise = (sz, BitmapIndexed (m1 .|. m2) (A.pair t2 t1))