diff --git a/distribution/changelog.txt b/distribution/changelog.txt
index bc9f9e3cca..c52a296f86 100644
--- a/distribution/changelog.txt
+++ b/distribution/changelog.txt
@@ -5,6 +5,7 @@
 - Feature: [#11306] Path additions are now kept when replacing the path.
 - Fix: [#6119]: Advertising campaign for ride window not updated properly (original bug).
 - Fix: [#11072] Land and water tools working out of bounds (original bug).
+- Fix: [#11259] Custom JSON object breaks saves.
 - Fix: [#11315] Ride that has never opened is shown as favorite ride of many guests.
 - Improved: [#6530] Allow water and land height changes on park borders.
 
diff --git a/src/openrct2/object/Object.h b/src/openrct2/object/Object.h
index faa521910d..eb02e35cbf 100644
--- a/src/openrct2/object/Object.h
+++ b/src/openrct2/object/Object.h
@@ -176,6 +176,7 @@ private:
     StringTable _stringTable;
     ImageTable _imageTable;
     std::vector<uint8_t> _sourceGames;
+    bool _isJsonObject{};
 
 protected:
     StringTable& GetStringTable()
@@ -199,6 +200,16 @@ public:
     explicit Object(const rct_object_entry& entry);
     virtual ~Object();
 
+    void MarkAsJsonObject()
+    {
+        _isJsonObject = true;
+    }
+
+    bool IsJsonObject() const
+    {
+        return _isJsonObject;
+    };
+
     // Legacy data structures
     const char* GetIdentifier() const
     {
diff --git a/src/openrct2/object/ObjectFactory.cpp b/src/openrct2/object/ObjectFactory.cpp
index d5211c71f6..0b86ba2048 100644
--- a/src/openrct2/object/ObjectFactory.cpp
+++ b/src/openrct2/object/ObjectFactory.cpp
@@ -429,6 +429,7 @@ namespace ObjectFactory
                 std::memcpy(entry.name, originalName.c_str(), minLength);
 
                 result = CreateObject(entry);
+                result->MarkAsJsonObject();
                 auto readContext = ReadObjectContext(objectRepository, id, !gOpenRCT2NoGraphics, fileRetriever);
                 result->ReadJson(&readContext, jRoot);
                 if (readContext.WasError())
diff --git a/src/openrct2/object/ObjectManager.cpp b/src/openrct2/object/ObjectManager.cpp
index 2be3024d77..51dd835f95 100644
--- a/src/openrct2/object/ObjectManager.cpp
+++ b/src/openrct2/object/ObjectManager.cpp
@@ -207,7 +207,8 @@ public:
         for (size_t i = 0; i < numObjects; i++)
         {
             const ObjectRepositoryItem* item = &_objectRepository.GetObjects()[i];
-            if (item->LoadedObject != nullptr && IsObjectCustom(item) && item->LoadedObject->GetLegacyData() != nullptr)
+            if (item->LoadedObject != nullptr && IsObjectCustom(item) && item->LoadedObject->GetLegacyData() != nullptr
+                && !item->LoadedObject->IsJsonObject())
             {
                 objects.push_back(item);
             }