diff --git a/test/Test/Data/List/ApplyMerge/New.hs b/test/Test/Data/List/ApplyMerge/New.hs
index b89d2ea..abc1f0c 100644
--- a/test/Test/Data/List/ApplyMerge/New.hs
+++ b/test/Test/Data/List/ApplyMerge/New.hs
@@ -3,16 +3,20 @@
 module Test.Data.List.ApplyMerge.New (tests) where
 
 import Control.Applicative (liftA2)
-import Data.Bifunctor (bimap)
+import Control.Arrow ((>>>))
+import Data.Bifunctor (bimap, second)
 import Data.Function (on)
 import Data.List (sort)
 import Data.List qualified as List
 import Data.List.ApplyMerge (applyMerge, applyMergeBy, applyMergeOn)
+import Data.List.NonEmpty (NonEmpty ((:|)))
+import Data.List.NonEmpty qualified as NE
+import Data.List.NonEmpty.ApplyMerge qualified as NE
 import Numeric.Natural (Natural)
 import Test.QuickCheck.Instances.Natural ()
 import Test.QuickCheck.Instances.Text ()
 import Test.Tasty (TestTree, testGroup)
-import Test.Tasty.QuickCheck (getInfiniteList, (===), getNonNegative)
+import Test.Tasty.QuickCheck (getInfiniteList, getNonNegative, (===))
 import Test.Tasty.QuickCheck qualified as QC
 
 tests :: TestTree
@@ -29,11 +33,46 @@ tests =
              in testApplyMerge applyMergeViaOn "f = (,)" "proj",
           testGroup "applyMerge cmp f xs ys" . List.singleton $
             testApplyMerge (applyMergeBy compare) "cmp = compare" "f"
+        ],
+      testGroup
+        "NonEmpty"
+        [ testNEApplyMerge NE.applyMerge "applyMerge f xs ys" "f",
+          testGroup "applyMergeOn proj f xs ys" . List.singleton $
+            let applyMergeViaOn :: NEApplyMerge
+                applyMergeViaOn f xs ys =
+                  NE.map (uncurry f) (NE.applyMergeOn (uncurry f) (,) xs ys)
+             in testNEApplyMerge applyMergeViaOn "f = (,)" "proj",
+          testGroup "applyMerge cmp f xs ys" . List.singleton $
+            testNEApplyMerge (NE.applyMergeBy compare) "cmp = compare" "f"
         ]
     ]
 
 type ApplyMerge = forall a b c. (Ord c) => (a -> b -> c) -> [a] -> [b] -> [c]
 
+type NEApplyMerge =
+  forall a b c.
+  (Ord c) =>
+  (a -> b -> c) ->
+  NonEmpty a ->
+  NonEmpty b ->
+  NonEmpty c
+
+testNEApplyMerge :: NEApplyMerge -> String -> String -> TestTree
+testNEApplyMerge am label funcLabel =
+  testGroup
+    label
+    [ testNEFunctions
+        ("increasing " <> funcLabel <> ", increasing xs and ys")
+        am
+        increasingNaturalFuncs
+        (+),
+      testNEFunctions
+        ("decreasing " <> funcLabel <> ", decreasing xs and ys")
+        am
+        decreasingIntegerFuncs
+        (-)
+    ]
+
 testApplyMerge :: ApplyMerge -> String -> String -> TestTree
 testApplyMerge am label funcLabel =
   testGroup
@@ -50,6 +89,37 @@ testApplyMerge am label funcLabel =
         (-)
     ]
 
+testNEFunctions ::
+  forall a.
+  (Show a, Integral a, QC.Arbitrary a) =>
+  String ->
+  NEApplyMerge ->
+  [(String, a -> a -> a)] ->
+  (a -> a -> a) ->
+  TestTree
+testNEFunctions label am funcs op =
+  QC.testProperty label $ do
+    (fName, f) <- QC.elements funcs
+    let limit = 100
+    let getOrderedList ::
+          ( QC.NonNegative a,
+            Either [QC.NonNegative a] (QC.InfiniteList (QC.NonNegative a))
+          ) ->
+          NonEmpty a
+        getOrderedList =
+          second (either id getInfiniteList)
+            >>> uncurry (:|)
+            >>> NE.map QC.getNonNegative
+            >>> NE.scanl1 op
+    pure . QC.counterexample fName $
+      \(getOrderedList -> xs) (getOrderedList -> ys) ->
+        let actual = am f xs ys
+            expected = NE.sort $ on (liftA2 f) (take1 limit) xs ys
+         in on (===) (NE.take limit) actual expected
+
+take1 :: Int -> NonEmpty a -> NonEmpty a
+take1 n (x :| xs) = x :| take n xs
+
 testFunctions ::
   forall a.
   (Show a, Integral a, QC.Arbitrary a) =>