diff --git a/lib/github_changelog_generator/fetcher.rb b/lib/github_changelog_generator/fetcher.rb
index 5e08ff9..5fb3c57 100644
--- a/lib/github_changelog_generator/fetcher.rb
+++ b/lib/github_changelog_generator/fetcher.rb
@@ -15,7 +15,7 @@ module GitHubChangelogGenerator
     "This script can make only 50 requests to GitHub API per hour without token!"
 
     def initialize(options = {})
-      @options = options
+      @options = options || {}
 
       @logger = Logger.new(STDOUT)
       @logger.formatter = proc do |_severity, _datetime, _progname, msg|
@@ -28,8 +28,8 @@ module GitHubChangelogGenerator
       @tag_times_hash = {}
       github_options = { per_page: PER_PAGE_NUMBER }
       github_options[:oauth_token] = @github_token unless @github_token.nil?
-      github_options[:endpoint] = options[:github_endpoint] unless options[:github_endpoint].nil?
-      github_options[:site] = options[:github_endpoint] unless options[:github_site].nil?
+      github_options[:endpoint] = @options[:github_endpoint] unless @options[:github_endpoint].nil?
+      github_options[:site] = @options[:github_endpoint] unless @options[:github_site].nil?
 
       @github = check_github_response { Github.new github_options }
     end
diff --git a/lib/github_changelog_generator/generator/generator.rb b/lib/github_changelog_generator/generator/generator.rb
index 300fd25..3ac896d 100644
--- a/lib/github_changelog_generator/generator/generator.rb
+++ b/lib/github_changelog_generator/generator/generator.rb
@@ -18,13 +18,9 @@ module GitHubChangelogGenerator
     #   generator = GitHubChangelogGenerator::Generator.new
     #   content = generator.compound_changelog
     def initialize(options = nil)
-      @options = options
+      @options = options || {}
 
       @fetcher = GitHubChangelogGenerator::Fetcher.new @options
-
-      fetch_and_filter_tags
-
-      fetch_issues_and_pr
     end
 
     def fetch_issues_and_pr
diff --git a/lib/github_changelog_generator/generator/generator_generation.rb b/lib/github_changelog_generator/generator/generator_generation.rb
index 2c36461..5571359 100644
--- a/lib/github_changelog_generator/generator/generator_generation.rb
+++ b/lib/github_changelog_generator/generator/generator_generation.rb
@@ -4,6 +4,9 @@ module GitHubChangelogGenerator
     #
     # @return [String] Generated change log file
     def compound_changelog
+      fetch_and_filter_tags
+      fetch_issues_and_pr
+
       log = "# Change Log\n\n"
 
       if @options[:unreleased_only]
diff --git a/spec/unit/generator/generator_tags_spec.rb b/spec/unit/generator/generator_tags_spec.rb
new file mode 100644
index 0000000..989dcff
--- /dev/null
+++ b/spec/unit/generator/generator_tags_spec.rb
@@ -0,0 +1,29 @@
+describe GitHubChangelogGenerator::Generator do
+  describe "#get_filtered_tags" do
+    before(:all) do
+      @generator = GitHubChangelogGenerator::Generator.new
+    end
+
+    context "when between_tags nil" do
+      # before(:each) do
+      #   @generator.options = {}
+      # end
+      subject { @generator.get_filtered_tags(%w(1 2 3)) }
+      it { is_expected.to be_a(Array) }
+      it { is_expected.to match_array(%w(1 2 3)) }
+    end
+
+    context "when between_tags 1" do
+      # before(:each) do
+      #   @generator.options = {between_tags: ["1"]}
+      # end
+
+      subject do
+        @generator.instance_variable_set("@options", between_tags: ["1"])
+        @generator.get_filtered_tags(%w(1 2 3))
+      end
+      it { is_expected.to be_a(Array) }
+      it { is_expected.to match_array(%w(1)) }
+    end
+  end
+end