diff --git a/encoded_id-rails.gemspec b/encoded_id-rails.gemspec
index ff49617..1836e75 100644
--- a/encoded_id-rails.gemspec
+++ b/encoded_id-rails.gemspec
@@ -32,7 +32,7 @@ Gem::Specification.new do |spec|
   # Uncomment to register a new dependency of your gem
   spec.add_dependency "activesupport", ">= 6.0", "< 8.0"
   spec.add_dependency "activerecord", ">= 6.0", "< 8.0"
-  spec.add_dependency "encoded_id", "~> 1.0.0.rc3"
+  spec.add_dependency "encoded_id", "~> 1.0.0.rc4"
   spec.add_development_dependency "appraisal"
 
   # For more information and examples about making a new gem, check out our
diff --git a/lib/encoded_id/rails/encoder_methods.rb b/lib/encoded_id/rails/encoder_methods.rb
index dfe36d7..9045459 100644
--- a/lib/encoded_id/rails/encoder_methods.rb
+++ b/lib/encoded_id/rails/encoder_methods.rb
@@ -28,9 +28,9 @@ def encoded_id_coder(options = {})
         EncodedId::Rails::Coder.new(
           salt: options[:salt] || encoded_id_salt,
           id_length: options[:id_length] || config.id_length,
-          character_group_size: options[:character_group_size] || config.character_group_size,
+          character_group_size: options.key?(:character_group_size) ? options[:character_group_size] : config.character_group_size,
           alphabet: options[:alphabet] || config.alphabet,
-          separator: options[:separator] || config.group_separator
+          separator: options.key?(:separator) ? options[:separator] : config.group_separator
         )
       end
     end
diff --git a/test/encoded_id/test_rails.rb b/test/encoded_id/test_rails.rb
index 97f64ab..34998c2 100644
--- a/test/encoded_id/test_rails.rb
+++ b/test/encoded_id/test_rails.rb
@@ -156,6 +156,20 @@ def test_it_gets_encoded_id_with_options
     }))
   end
 
+  def test_it_gets_encoded_id_with_options_with_nil_group_size
+    assert_match(/[^_]+/, MyModel.encode_encoded_id(model.id, {
+      character_group_size: nil,
+      separator: "_"
+    }))
+  end
+
+  def test_it_gets_encoded_id_with_options_with_nil_group_size
+    assert_match(/.{8}/, MyModel.encode_encoded_id(model.id, {
+      character_group_size: 3,
+      separator: nil
+    }))
+  end
+
   def test_it_decodes_id
     assert_equal [model.id], MyModel.decode_encoded_id(model.encoded_id)
   end