diff --git a/tests/Instances.hs b/tests/Instances.hs
index e52c5ec..77d8fb5 100644
--- a/tests/Instances.hs
+++ b/tests/Instances.hs
@@ -36,7 +36,7 @@ instance (Integral i, Integral s, Eq a, Arbitrary a, Arbitrary l, Arbitrary sd)
       -- Pick a random window "number" in each workspace, to give focus.
       focus <- sequence [ if null windows
                           then return Nothing
-                          else liftM Just $ choose (0, length windows - 1)
+                          else Just <$> choose (0, length windows - 1)
                         | windows <- wsWindows ]
 
       let tags = [1 .. fromIntegral numWs]
@@ -80,7 +80,7 @@ newtype NonEmptyWindowsStackSet = NonEmptyWindowsStackSet T
 
 instance Arbitrary NonEmptyWindowsStackSet where
   arbitrary =
-    NonEmptyWindowsStackSet `fmap` (arbitrary `suchThat` (not . null . allWindows))
+    NonEmptyWindowsStackSet <$> (arbitrary `suchThat` (not . null . allWindows))
 
 instance Arbitrary Rectangle where
     arbitrary = Rectangle <$> arbitrary <*> arbitrary <*> arbitrary <*> arbitrary
@@ -99,7 +99,7 @@ newtype NonEmptyNubList a = NonEmptyNubList [a]
     deriving ( Eq, Ord, Show, Read )
 
 instance (Eq a, Arbitrary a) => Arbitrary (NonEmptyNubList a) where
-  arbitrary   = NonEmptyNubList `fmap` ((liftM nub arbitrary) `suchThat` (not . null))
+  arbitrary = NonEmptyNubList <$> ((nub <$> arbitrary) `suchThat` (not . null))
 
 
 
@@ -116,7 +116,7 @@ arbitraryTag :: T -> Gen Tag
 arbitraryTag x = do
   let ts = tags x
   -- There must be at least 1 workspace, thus at least 1 tag.
-  idx <- choose (0, (length ts) - 1)
+  idx <- choose (0, length ts - 1)
   return $ ts!!idx
 
 -- | Pull out an arbitrary window from a StackSet that is guaranteed to have a
@@ -136,5 +136,5 @@ arbitraryWindow :: NonEmptyWindowsStackSet -> Gen Window
 arbitraryWindow (NonEmptyWindowsStackSet x) = do
   let ws = allWindows x
   -- We know that there are at least 1 window in a NonEmptyWindowsStackSet.
-  idx <- choose(0, (length ws) - 1)
+  idx <- choose (0, length ws - 1)
   return $ ws!!idx
diff --git a/tests/Properties/Delete.hs b/tests/Properties/Delete.hs
index a8b8dd1..fed3409 100644
--- a/tests/Properties/Delete.hs
+++ b/tests/Properties/Delete.hs
@@ -64,7 +64,7 @@ prop_delete_focus_not_end = do
        -- last one in the stack.
        `suchThat` \(x' :: T) ->
          let currWins = index x'
-         in length (currWins) >= 2 && peek x' /= Just (last currWins)
+         in length currWins >= 2 && peek x' /= Just (last currWins)
   -- This is safe, as we know there are >= 2 windows
   let Just n = peek x
   return $ peek (delete n x) == peek (focusDown x)
diff --git a/tests/Properties/Focus.hs b/tests/Properties/Focus.hs
index 6bc0055..a3ea84e 100644
--- a/tests/Properties/Focus.hs
+++ b/tests/Properties/Focus.hs
@@ -32,8 +32,8 @@ prop_focusWindow_master (NonNegative n) (x :: T) =
                    in index (focusWindow (s !! i) x) == index x
 
 -- shifting focus is trivially reversible
-prop_focus_left  (x :: T) = (focusUp  (focusDown x)) == x
-prop_focus_right (x :: T) = (focusDown (focusUp  x)) ==  x
+prop_focus_left  (x :: T) = focusUp  (focusDown x) == x
+prop_focus_right (x :: T) = focusDown (focusUp  x) == x
 
 -- focus master is idempotent
 prop_focusMaster_idem (x :: T) = focusMaster x == focusMaster (focusMaster x)
@@ -47,9 +47,9 @@ prop_focusWindow_works (NonNegative (n :: Int)) (x :: T) =
                    in (focus . fromJust . stack . workspace . current) (focusWindow (s !! i) x) == (s !! i)
 
 -- rotation through the height of a stack gets us back to the start
-prop_focus_all_l (x :: T) = (foldr (const focusUp) x [1..n]) == x
+prop_focus_all_l (x :: T) = foldr (const focusUp) x [1..n] == x
   where n = length (index x)
-prop_focus_all_r (x :: T) = (foldr (const focusDown) x [1..n]) == x
+prop_focus_all_r (x :: T) = foldr (const focusDown) x [1..n] == x
   where n = length (index x)
 
 -- prop_rotate_all (x :: T) = f (f x) == f x
diff --git a/tests/Properties/GreedyView.hs b/tests/Properties/GreedyView.hs
index 3f2eb9b..09dd1b8 100644
--- a/tests/Properties/GreedyView.hs
+++ b/tests/Properties/GreedyView.hs
@@ -35,7 +35,7 @@ prop_greedyView_local  (x :: T) = do
 -- greedyView is idempotent
 prop_greedyView_idem (x :: T) = do
   n <- arbitraryTag x
-  return $ greedyView n (greedyView n x) == (greedyView n x)
+  return $ greedyView n (greedyView n x) == greedyView n x
 
 -- greedyView is reversible, though shuffles the order of hidden/visible
 prop_greedyView_reversible (x :: T) = do
diff --git a/tests/Properties/Insert.hs b/tests/Properties/Insert.hs
index c277795..6730269 100644
--- a/tests/Properties/Insert.hs
+++ b/tests/Properties/Insert.hs
@@ -46,7 +46,7 @@ prop_insert_delete x = do
 
 -- inserting n elements increases current stack size by n
 prop_size_insert is (EmptyStackSet x) =
-        size (foldr insertUp x ws ) ==  (length ws)
+        size (foldr insertUp x ws) == length ws
   where
     ws   = nub is
     size = length . index
diff --git a/tests/Properties/Layout/Full.hs b/tests/Properties/Layout/Full.hs
index eca6ec3..3bb8d60 100644
--- a/tests/Properties/Layout/Full.hs
+++ b/tests/Properties/Layout/Full.hs
@@ -29,6 +29,6 @@ prop_purelayout_full rect = do
 
 -- what happens when we send an IncMaster message to Full --- Nothing
 prop_sendmsg_full (NonNegative k) =
-         isNothing (Full `pureMessage` (SomeMessage (IncMasterN k)))
+         isNothing (Full `pureMessage` SomeMessage (IncMasterN k))
 
 prop_desc_full = description Full == show Full
diff --git a/tests/Properties/Layout/Tall.hs b/tests/Properties/Layout/Tall.hs
index 5353e62..45cfe72 100644
--- a/tests/Properties/Layout/Tall.hs
+++ b/tests/Properties/Layout/Tall.hs
@@ -29,12 +29,12 @@ prop_tile_non_overlap rect windows nmaster = noOverlaps (tile pct rect nmaster w
 
 -- splitting horizontally yields sensible results
 prop_split_horizontal (NonNegative n) x =
-      (noOverflows (+) (rect_x x) (rect_width x)) ==>
+      noOverflows (+) (rect_x x) (rect_width x) ==>
         sum (map rect_width xs) == rect_width x
      &&
-        all (== rect_height x) (map rect_height xs)
+        all (\s -> rect_height s == rect_height x) xs
      &&
-        (map rect_x xs) == (sort $ map rect_x xs)
+        map rect_x xs == sort (map rect_x xs)
 
     where
         xs = splitHorizontally n x
@@ -72,7 +72,7 @@ prop_shrink_tall (NonNegative n) (Positive delta) (NonNegative frac) =
         -- remaining fraction should shrink
     where
          l1                   = Tall n delta frac
-         Just l2@(Tall n' delta' frac') = l1 `pureMessage` (SomeMessage Shrink)
+         Just l2@(Tall n' delta' frac') = l1 `pureMessage` SomeMessage Shrink
         --  pureMessage :: layout a -> SomeMessage -> Maybe (layout a)
 
 
@@ -93,7 +93,7 @@ prop_expand_tall (NonNegative n)
     where
          frac                 = min 1 (n1 % d1)
          l1                   = Tall n delta frac
-         Just l2@(Tall n' delta' frac') = l1 `pureMessage` (SomeMessage Expand)
+         Just l2@(Tall n' delta' frac') = l1 `pureMessage` SomeMessage Expand
         --  pureMessage :: layout a -> SomeMessage -> Maybe (layout a)
 
 -- what happens when we send an IncMaster message to Tall
@@ -102,7 +102,7 @@ prop_incmaster_tall (NonNegative n) (Positive delta) (NonNegative frac)
        delta == delta'  && frac == frac' && n' == n + k
     where
          l1                   = Tall n delta frac
-         Just l2@(Tall n' delta' frac') = l1 `pureMessage` (SomeMessage (IncMasterN k))
+         Just l2@(Tall n' delta' frac') = l1 `pureMessage` SomeMessage (IncMasterN k)
         --  pureMessage :: layout a -> SomeMessage -> Maybe (layout a)
 
 
diff --git a/tests/Properties/Screen.hs b/tests/Properties/Screen.hs
index b679fb9..b3d3468 100644
--- a/tests/Properties/Screen.hs
+++ b/tests/Properties/Screen.hs
@@ -53,8 +53,8 @@ prop_aspect_hint_shrink hint (w,h) = case applyAspectHint hint (w,h) of
 -- the desired range
 prop_aspect_fits =
     forAll ((,,,) <$> pos <*> pos <*> pos <*> pos) $ \ (x,y,a,b) ->
-    let f v = applyAspectHint ((x, y+a), (x+b, y)) v
-    in  and [ noOverflows (*) x (y+a), noOverflows (*) (x+b) y ]
+    let f = applyAspectHint ((x, y+a), (x+b, y))
+    in  noOverflows (*) x (y+a) && noOverflows (*) (x+b) y
             ==> f (x,y) == (x,y)
 
   where pos = choose (0, 65535)
diff --git a/tests/Properties/Shift.hs b/tests/Properties/Shift.hs
index 2150cbf..144b19f 100644
--- a/tests/Properties/Shift.hs
+++ b/tests/Properties/Shift.hs
@@ -27,7 +27,7 @@ prop_shift_reversible (x :: T) = do
 -- shiftMaster
 
 -- focus/local/idempotent same as swapMaster:
-prop_shift_master_focus (x :: T) = peek x == (peek $ shiftMaster x)
+prop_shift_master_focus (x :: T) = peek x == peek (shiftMaster x)
 prop_shift_master_local (x :: T) = hidden_spaces x == hidden_spaces (shiftMaster x)
 prop_shift_master_idempotent (x :: T) = shiftMaster (shiftMaster x) == shiftMaster x
 -- ordering is constant modulo the focused window:
@@ -57,14 +57,14 @@ prop_shift_win_fix_current = do
   x <- arbitrary `suchThat` \(x' :: T) ->
          -- Invariant, otherWindows are NOT in the current workspace.
          let otherWindows = allWindows x' L.\\ index x'
-         in  length(tags x') >= 2 && length(otherWindows) >= 1
+         in  length (tags x') >= 2 && not (null otherWindows)
   -- Sadly we have to construct `otherWindows` again, for the actual StackSet
   -- that got chosen.
   let otherWindows = allWindows x L.\\ index x
   -- We know such tag must exists, due to the precondition
   n <- arbitraryTag x `suchThat` (/= currentTag x)
   -- we know length is >= 1, from above precondition
-  idx <- choose(0, length(otherWindows) - 1)
+  idx <- choose (0, length otherWindows - 1)
   let w = otherWindows !! idx
-  return $ (current $ x) == (current $ shiftWin n w x)
+  return $ current x == current (shiftWin n w x)
 
diff --git a/tests/Properties/Stack.hs b/tests/Properties/Stack.hs
index 344c4c3..f85ca3e 100644
--- a/tests/Properties/Stack.hs
+++ b/tests/Properties/Stack.hs
@@ -1,6 +1,10 @@
 {-# LANGUAGE CPP #-}
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+
+#ifdef VERSION_quickcheck_classes
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+#endif
+
 module Properties.Stack where
 
 import Test.QuickCheck
@@ -24,7 +28,7 @@ import Test.QuickCheck.Classes (
 -- windows kept in the zipper
 prop_index_length (x :: T) =
     case stack . workspace . current $ x of
-        Nothing   -> length (index x) == 0
+        Nothing -> null (index x)
         Just it -> length (index x) == length (focus it : up it ++ down it)
 
 
@@ -43,7 +47,7 @@ prop_allWindowsMember (NonEmptyWindowsStackSet x) = do
       -- which is a key component in this test (together with member).
   let ws = allWindows x
   -- We know that there are at least 1 window in a NonEmptyWindowsStackSet.
-  idx <- choose(0, (length ws) - 1)
+  idx <- choose (0, length ws - 1)
   return $ member (ws!!idx) x
 
 
@@ -56,8 +60,8 @@ prop_filter_order (x :: T) =
 -- differentiate should return Nothing if the list is empty or Just stack, with
 -- the first element of the list is current, and the rest of the list is down.
 prop_differentiate xs =
-        if null xs then differentiate xs == Nothing
-                   else (differentiate xs) == Just (Stack (head xs) [] (tail xs))
+        if null xs then isNothing (differentiate xs)
+                   else differentiate xs == Just (Stack (head xs) [] (tail xs))
     where _ = xs :: [Int]
 
 
diff --git a/tests/Properties/StackSet.hs b/tests/Properties/StackSet.hs
index 7fc5192..0b1e8f1 100644
--- a/tests/Properties/StackSet.hs
+++ b/tests/Properties/StackSet.hs
@@ -58,7 +58,7 @@ invariant (s :: T) = and
 --  inBounds  = and [ w >=0 && w < size s | (w,sc) <- M.assocs (screens s) ]
 
 monotonic []       = True
-monotonic (x:[])   = True
+monotonic [x]      = True
 monotonic (x:y:zs) | x == y-1  = monotonic (y:zs)
                    | otherwise = False
 
@@ -126,7 +126,7 @@ prop_empty (EmptyStackSet x) =
 prop_empty_current (EmptyStackSet x) = currentTag x == head (tags x)
 
 -- no windows will be a member of an empty workspace
-prop_member_empty i (EmptyStackSet x) = member i x == False
+prop_member_empty i (EmptyStackSet x) = not (member i x)
 
 -- peek either yields nothing on the Empty workspace, or Just a valid window
 prop_member_peek (x :: T) =
diff --git a/tests/Properties/Swap.hs b/tests/Properties/Swap.hs
index a516f2c..fb8e529 100644
--- a/tests/Properties/Swap.hs
+++ b/tests/Properties/Swap.hs
@@ -11,8 +11,8 @@ import XMonad.StackSet hiding (filter)
 -- swapUp, swapDown, swapMaster: reordiring windows
 
 -- swap is trivially reversible
-prop_swap_left  (x :: T) = (swapUp  (swapDown x)) == x
-prop_swap_right (x :: T) = (swapDown (swapUp  x)) ==  x
+prop_swap_left  (x :: T) = swapUp  (swapDown x) == x
+prop_swap_right (x :: T) = swapDown (swapUp  x) ==  x
 -- TODO swap is reversible
 -- swap is reversible, but involves moving focus back the window with
 -- master on it. easy to do with a mouse...
@@ -26,12 +26,12 @@ prop_promote_reversible x b = (not . null . fromMaybe [] . flip index x . curren
 -}
 
 -- swap doesn't change focus
-prop_swap_master_focus (x :: T) = peek x == (peek $ swapMaster x)
+prop_swap_master_focus (x :: T) = peek x == peek (swapMaster x)
 --    = case peek x of
 --        Nothing -> True
 --        Just f  -> focus (stack (workspace $ current (swap x))) == f
-prop_swap_left_focus   (x :: T) = peek x == (peek $ swapUp   x)
-prop_swap_right_focus  (x :: T) = peek x == (peek $ swapDown  x)
+prop_swap_left_focus   (x :: T) = peek x == peek (swapUp   x)
+prop_swap_right_focus  (x :: T) = peek x == peek (swapDown  x)
 
 -- swap is local
 prop_swap_master_local (x :: T) = hidden_spaces x == hidden_spaces (swapMaster x)
@@ -39,9 +39,9 @@ prop_swap_left_local   (x :: T) = hidden_spaces x == hidden_spaces (swapUp   x)
 prop_swap_right_local  (x :: T) = hidden_spaces x == hidden_spaces (swapDown  x)
 
 -- rotation through the height of a stack gets us back to the start
-prop_swap_all_l (x :: T) = (foldr (const swapUp)  x [1..n]) == x
+prop_swap_all_l (x :: T) = foldr (const swapUp)  x [1..n] == x
   where n = length (index x)
-prop_swap_all_r (x :: T) = (foldr (const swapDown) x [1..n]) == x
+prop_swap_all_r (x :: T) = foldr (const swapDown) x [1..n] == x
   where n = length (index x)
 
 prop_swap_master_idempotent (x :: T) = swapMaster (swapMaster x) == swapMaster x
diff --git a/tests/Properties/View.hs b/tests/Properties/View.hs
index ef9b58d..fe56ba3 100644
--- a/tests/Properties/View.hs
+++ b/tests/Properties/View.hs
@@ -37,7 +37,7 @@ prop_view_local  (x :: T) = do
 -- view is idempotent
 prop_view_idem (x :: T) = do
     n <- arbitraryTag x
-    return $ view n (view n x) == (view n x)
+    return $ view n (view n x) == view n x
 
 -- view is reversible, though shuffles the order of hidden/visible
 prop_view_reversible (x :: T) = do
diff --git a/tests/Utils.hs b/tests/Utils.hs
index e3eef0f..4ae4416 100644
--- a/tests/Utils.hs
+++ b/tests/Utils.hs
@@ -12,8 +12,8 @@ hidden_spaces x = map workspace (visible x) ++ hidden x
 -- normalise workspace list
 normal s = s { hidden = sortBy g (hidden s), visible = sortBy f (visible s) }
     where
-        f = \a b -> tag (workspace a) `compare` tag (workspace b)
-        g = \a b -> tag a `compare` tag b
+        f a b = tag (workspace a) `compare` tag (workspace b)
+        g a b = tag a `compare` tag b
 
 
 noOverlaps []  = True