diff --git a/aeson.cabal b/aeson.cabal
--- a/aeson.cabal
+++ b/aeson.cabal
@@ -1,5 +1,5 @@
 name:            aeson
-version:         0.11.2.0
+version:         0.11.2.1
 license:         BSD3
 license-file:    LICENSE
 category:        Text, Web, JSON
@@ -113,7 +113,7 @@
 
   if !impl(ghc >= 7.10)
     -- `Numeric.Natural` is available in base only since GHC 7.10 / base 4.8
-    build-depends: nats >=1 && <1.1
+    build-depends: nats >=1 && <1.2
 
   if flag(old-locale)
     build-depends: time < 1.5, old-locale
@@ -149,7 +149,7 @@
 
   build-depends:
     HUnit,
-    QuickCheck >= 2.7 && <2.8.3,
+    QuickCheck >= 2.7 && <2.10,
     aeson,
     attoparsec,
     base,
@@ -178,7 +178,7 @@
     build-depends: time >= 1.5
 
   if !impl(ghc >= 7.10)
-    build-depends: nats >=1 && <1.1
+    build-depends: nats >=1 && <1.2
 
 source-repository head
   type:     git
diff --git a/tests/Instances.hs b/tests/Instances.hs
--- a/tests/Instances.hs
+++ b/tests/Instances.hs
@@ -142,12 +142,17 @@
 instance (ApproxEq a) => ApproxEq [a] where
     a =~ b = length a == length b && all (uncurry (=~)) (zip a b)
 
+#if !MIN_VERSION_QuickCheck(2,9,0)
 instance Arbitrary Version where
     arbitrary = makeVersion . fmap getNonNegative <$> resize 4 (listOf1 arbitrary)
 
 instance Arbitrary a => Arbitrary (NonEmpty a) where
     arbitrary = (:|) <$> arbitrary <*> arbitrary
 
+instance Arbitrary a => Arbitrary (Const a b) where
+    arbitrary = Const <$> arbitrary
+#endif
+
 -- Version tags are deprecated, so we avoid using them in the Arbitrary
 -- instance. However, the recommended constructor 'makeVersion' is not
 -- exported by "Data.Version" until base-4.8.0.0. For previous versions,
@@ -168,6 +173,3 @@
 
 instance Arbitrary b => Arbitrary (Tagged a b) where
     arbitrary = Tagged <$> arbitrary
-
-instance Arbitrary a => Arbitrary (Const a b) where
-    arbitrary = Const <$> arbitrary