diff --git a/firebase_core/_firebase_database_collection_vm/CHANGELOG.md b/firebase_core/_firebase_database_collection_vm/CHANGELOG.md
index 2e2e7561..f79b31c9 100644
--- a/firebase_core/_firebase_database_collection_vm/CHANGELOG.md
+++ b/firebase_core/_firebase_database_collection_vm/CHANGELOG.md
@@ -1,5 +1,7 @@
-## 0.0.2+1
+## 0.0.3
+- add unionWith to sorted set to mirror Web SDK.
 
+## 0.0.2+1
 - constrain test, collection, meta dependency
 
 ## 0.0.2
diff --git a/firebase_core/_firebase_database_collection_vm/lib/src/immutable_sorted_set.dart b/firebase_core/_firebase_database_collection_vm/lib/src/immutable_sorted_set.dart
index bf4e2aef..bd86d977 100644
--- a/firebase_core/_firebase_database_collection_vm/lib/src/immutable_sorted_set.dart
+++ b/firebase_core/_firebase_database_collection_vm/lib/src/immutable_sorted_set.dart
@@ -33,6 +33,22 @@ class ImmutableSortedSet<T> extends Iterable<T> {
     return ImmutableSortedSet<T>._(_map.insert(entry, null));
   }
 
+  ImmutableSortedSet<T> unionWith(ImmutableSortedSet<T> other) {
+    ImmutableSortedSet<T> result = this;
+
+    // Make sure `result` always refers to the larger one of the two sets.
+    if (result.length < other.length) {
+      result = other;
+      other = this;
+    }
+
+    for (T elem in other) {
+      result = result.insert(elem);
+    }
+
+    return result;
+  }
+
   T get minEntry => _map.minKey;
 
   T get maxEntry => _map.maxKey;
@@ -70,10 +86,7 @@ class ImmutableSortedSet<T> extends Iterable<T> {
 
   @override
   bool operator ==(Object other) =>
-      identical(this, other) ||
-      other is ImmutableSortedSet &&
-          runtimeType == other.runtimeType &&
-          _map == other._map;
+      identical(this, other) || other is ImmutableSortedSet && runtimeType == other.runtimeType && _map == other._map;
 
   @override
   int get hashCode => _map.hashCode;
diff --git a/firebase_core/_firebase_database_collection_vm/pubspec.yaml b/firebase_core/_firebase_database_collection_vm/pubspec.yaml
index af915ad1..494cfda9 100644
--- a/firebase_core/_firebase_database_collection_vm/pubspec.yaml
+++ b/firebase_core/_firebase_database_collection_vm/pubspec.yaml
@@ -1,6 +1,6 @@
 name: _firebase_database_collection_vm
 description: For internal use of the Firestore and Realtime Database packages
-version: 0.0.2+1
+version: 0.0.3
 homepage: https://github.com/fluttercommunity/firebase_flutter_sdk
 
 environment:
@@ -9,4 +9,6 @@ environment:
 dev_dependencies:
   test: '>=1.0.0 <2.0.0'
   dart_quickcheck:
-    git: https://github.com/long1eu/dart_quickcheck.git
\ No newline at end of file
+    git: https://github.com/long1eu/dart_quickcheck.git
+
+latest_commit: a94d79a90b737dde059fc53a56ed21c22e2498ee
\ No newline at end of file