diff --git a/src/impl/realm_coordinator.cpp b/src/impl/realm_coordinator.cpp
index 931416b8..42f8aba9 100644
--- a/src/impl/realm_coordinator.cpp
+++ b/src/impl/realm_coordinator.cpp
@@ -102,7 +102,7 @@ std::shared_ptr<Realm> RealmCoordinator::get_realm(Realm::Config config)
             }
         }
     }
-    
+
     auto realm = std::make_shared<Realm>(std::move(config));
     realm->init(shared_from_this());
 
diff --git a/src/object_store.hpp b/src/object_store.hpp
index 0b9f05f8..670cbf53 100644
--- a/src/object_store.hpp
+++ b/src/object_store.hpp
@@ -157,7 +157,7 @@ namespace realm {
       private:
         std::vector<ObjectSchemaValidationException> m_validation_errors;
     };
-    
+
     class SchemaMismatchException : public ObjectStoreException {
     public:
         SchemaMismatchException(std::vector<ObjectSchemaValidationException> const& errors);
diff --git a/src/shared_realm.cpp b/src/shared_realm.cpp
index c5d50b8e..056bc9e7 100644
--- a/src/shared_realm.cpp
+++ b/src/shared_realm.cpp
@@ -463,10 +463,10 @@ void Realm::close()
     m_coordinator = nullptr;
 }
 
-int Realm::file_format_upgraded_from_version() const
+util::Optional<int> Realm::file_format_upgraded_from_version() const
 {
     if (upgrade_initial_version != upgrade_final_version) {
         return upgrade_initial_version;
     }
-    return 0;
+    return util::Optional<int>();
 }
diff --git a/src/shared_realm.hpp b/src/shared_realm.hpp
index d01bfdb1..1536fa76 100644
--- a/src/shared_realm.hpp
+++ b/src/shared_realm.hpp
@@ -133,7 +133,7 @@ namespace realm {
         void close();
 
         // returns the file format version upgraded from, or 0 if not upgraded
-        int file_format_upgraded_from_version() const;
+        util::Optional<int> file_format_upgraded_from_version() const;
 
         ~Realm();