diff --git a/lib/active_model/serializer/collection_serializer.rb b/lib/active_model/serializer/collection_serializer.rb
index 02258838..7862e994 100644
--- a/lib/active_model/serializer/collection_serializer.rb
+++ b/lib/active_model/serializer/collection_serializer.rb
@@ -14,7 +14,7 @@ module ActiveModel
           serializer_context_class = options.fetch(:serializer_context_class, ActiveModel::Serializer)
           serializer_class = options.fetch(:serializer) { serializer_context_class.serializer_for(resource) }
 
-          if serializer_class.nil?
+          if serializer_class.nil? # rubocop:disable Style/GuardClause
             fail NoSerializerError, "No serializer found for resource: #{resource.inspect}"
           else
             serializer_class.new(resource, options.except(:serializer))
diff --git a/lib/active_model_serializers/adapter.rb b/lib/active_model_serializers/adapter.rb
index 5a914b0c..35adbccd 100644
--- a/lib/active_model_serializers/adapter.rb
+++ b/lib/active_model_serializers/adapter.rb
@@ -1,7 +1,7 @@
 module ActiveModelSerializers
   module Adapter
     UnknownAdapterError = Class.new(ArgumentError)
-    ADAPTER_MAP = {}.freeze
+    ADAPTER_MAP = {} # rubocop:disable Style/MutableConstant
     private_constant :ADAPTER_MAP if defined?(private_constant)
     require 'active_model_serializers/adapter/fragment_cache'
     require 'active_model_serializers/adapter/cached_serializer'
diff --git a/lib/active_model_serializers/adapter/json_api/relationship.rb b/lib/active_model_serializers/adapter/json_api/relationship.rb
index 63d3e5d5..30e5a091 100644
--- a/lib/active_model_serializers/adapter/json_api/relationship.rb
+++ b/lib/active_model_serializers/adapter/json_api/relationship.rb
@@ -38,12 +38,10 @@ module ActiveModelSerializers
         def data_for(serializer, options)
           if serializer.respond_to?(:each)
             serializer.map { |s| ResourceIdentifier.new(s).as_json }
-          else
-            if options[:virtual_value]
-              options[:virtual_value]
-            elsif serializer && serializer.object
-              ResourceIdentifier.new(serializer).as_json
-            end
+          elsif options[:virtual_value]
+            options[:virtual_value]
+          elsif serializer && serializer.object
+            ResourceIdentifier.new(serializer).as_json
           end
         end
       end