diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,8 @@
-## [_Unreleased_](https://github.com/freckle/hspec-expectations-json/compare/v1.0.1.0...main)
+## [_Unreleased_](https://github.com/freckle/hspec-expectations-json/compare/v1.0.2.1...main)
+
+## [v1.0.2.1](https://github.com/freckle/hspec-expectations-json/compare/v1.0.2.0...v1.0.2.1)
+
+- Fixed issue with `expandHeterogenousArrays` not working for nested Objects
 
 ## [v1.0.2.0](https://github.com/freckle/hspec-expectations-json/compare/v1.0.1.1...v1.0.2.0)
 
diff --git a/hspec-expectations-json.cabal b/hspec-expectations-json.cabal
--- a/hspec-expectations-json.cabal
+++ b/hspec-expectations-json.cabal
@@ -1,6 +1,6 @@
 cabal-version:   1.18
 name:            hspec-expectations-json
-version:         1.0.2.0
+version:         1.0.2.1
 license:         MIT
 license-file:    LICENSE
 copyright:       2020 Freckle Education
@@ -59,15 +59,15 @@
         TypeApplications TypeFamilies
 
     build-depends:
-        Diff,
-        HUnit,
-        aeson,
-        aeson-pretty,
+        Diff >=0.3.4,
+        HUnit >=1.6.0.0,
+        aeson >=1.3.1.1,
+        aeson-pretty >=0.8.7,
         base >=4.11 && <5,
-        scientific,
-        text,
-        unordered-containers,
-        vector
+        scientific >=0.3.6.2,
+        text >=1.2.3.1,
+        unordered-containers >=0.2.9.0,
+        vector >=0.12.0.2
 
 test-suite spec
     type:               exitcode-stdio-1.0
@@ -89,9 +89,9 @@
         TypeApplications TypeFamilies
 
     build-depends:
-        QuickCheck,
-        aeson,
-        aeson-qq,
+        QuickCheck >=2.11.3,
+        aeson >=1.3.1.1,
+        aeson-qq >=0.8.2,
         base >=4.11 && <5,
-        hspec,
+        hspec >=2.5.5,
         hspec-expectations-json
diff --git a/library/Test/Hspec/Expectations/Json/Internal.hs b/library/Test/Hspec/Expectations/Json/Internal.hs
--- a/library/Test/Hspec/Expectations/Json/Internal.hs
+++ b/library/Test/Hspec/Expectations/Json/Internal.hs
@@ -102,14 +102,33 @@
 --
 -- ex: [{a:1}, {b:1}] -> [{a:1, b:null}, {a:null, b:1}]
 expandHeterogenousArrays :: Value -> Value
-expandHeterogenousArrays = go KeyMap.empty
+expandHeterogenousArrays = go mempty
  where
   collectAllKeys = \case
     Object km -> Null <$ km
     _ -> KeyMap.empty
-  go allKeys = \case
-    Object km -> Object $ expandHeterogenousArrays <$> KeyMap.union km allKeys
-    Array vec -> Array $ go (foldMap collectAllKeys vec) <$> vec
+  go vec = \case
+    Object km ->
+      let
+        -- Set all keys not present in this level of the object to null
+        nullCurrentLevel :: Object
+        nullCurrentLevel = KeyMap.union km (foldMap collectAllKeys vec)
+        -- `mapWithKey` is not available for all version of `KeyMap`
+        mapWithKey f = KeyMap.fromList . fmap f . KeyMap.toList
+        -- Recurse over all properties
+        nullChildren :: Object -> Object
+        nullChildren = mapWithKey $ \(k, v) -> (k, go (siblingProperties k) v)
+        -- Gather all values at the specified key
+        siblingProperties k =
+          V.mapMaybe
+            ( \case
+                Object km' -> KeyMap.lookup k km'
+                _ -> Nothing
+            )
+            vec
+      in
+        Object $ nullChildren nullCurrentLevel
+    Array v -> Array $ go v <$> v
     x -> x
 
 newtype Sortable = Sortable Value
diff --git a/tests/Test/Hspec/Expectations/JsonSpec.hs b/tests/Test/Hspec/Expectations/JsonSpec.hs
--- a/tests/Test/Hspec/Expectations/JsonSpec.hs
+++ b/tests/Test/Hspec/Expectations/JsonSpec.hs
@@ -159,6 +159,57 @@
 
       a `shouldMatchJsonWithOmittedNullFields` b
 
+    it "ignores omitted null fields in nested objects" $ do
+      let
+        a =
+          [aesonQQ|
+[
+  {
+    "a": {
+      "a": 1
+    },
+    "b": {
+      "b": 1
+    }
+  },
+  {
+    "a": {
+      "b": 2
+    },
+    "b": {
+      "c": 2
+    }
+  }
+]
+|]
+        b =
+          [aesonQQ|
+[
+  {
+    "a": {
+      "a": 1,
+      "b": null
+    },
+    "b": {
+      "b": 1,
+      "c": null
+    }
+  },
+  {
+    "a": {
+      "a": null,
+      "b": 2
+    },
+    "b": {
+      "b": null,
+      "c": 2
+    }
+  }
+]
+|]
+
+      a `shouldMatchJsonWithOmittedNullFields` b
+
 -- it "is an example failure, to checking how they're printed" $ do
 --   let
 --     a = [aesonQQ|