diff --git a/lib/graphql/schema/build_from_definition.rb b/lib/graphql/schema/build_from_definition.rb
index b5b3cc614d..c213d57481 100644
--- a/lib/graphql/schema/build_from_definition.rb
+++ b/lib/graphql/schema/build_from_definition.rb
@@ -51,7 +51,7 @@ def build(schema_superclass, document, default_resolve:, using: {}, base_types:
             raise InvalidDocumentError.new('Must provide only one schema definition.')
           end
           schema_definition = schema_defns.first
-          types = {}
+          types = schema_superclass.types.dup
           directives = schema_superclass.directives.dup
           type_resolver = build_resolve_type(types, directives, ->(type_name) { types[type_name] ||= Schema::LateBoundType.new(type_name)})
           # Make a different type resolver because we need to coerce directive arguments