diff --git a/lib/github_changelog_generator/generator/generator_tags.rb b/lib/github_changelog_generator/generator/generator_tags.rb
index d8f4534ab..7568a1790 100644
--- a/lib/github_changelog_generator/generator/generator_tags.rb
+++ b/lib/github_changelog_generator/generator/generator_tags.rb
@@ -135,7 +135,7 @@ def filter_since_tag(all_tags)
                             []
                           end
         else
-          Helper.log.warn "Warning: can't find tag #{tag}, specified with --since-tag option."
+          raise ChangelogGeneratorError, "Error: can't find tag #{tag}, specified with --since-tag option."
         end
       end
       filtered_tags
@@ -155,7 +155,7 @@ def filter_due_tag(all_tags)
                             []
                           end
         else
-          Helper.log.warn "Warning: can't find tag #{tag}, specified with --due-tag option."
+          raise ChangelogGeneratorError, "Error: can't find tag #{tag}, specified with --due-tag option."
         end
       end
       filtered_tags
diff --git a/spec/unit/generator/generator_tags_spec.rb b/spec/unit/generator/generator_tags_spec.rb
index d9dc6b46c..515da2302 100644
--- a/spec/unit/generator/generator_tags_spec.rb
+++ b/spec/unit/generator/generator_tags_spec.rb
@@ -191,24 +191,16 @@ def tags_from_strings(tags_strings)
 
       context "with invalid since tag" do
         let(:generator) { GitHubChangelogGenerator::Generator.new(since_tag: "Invalid tag") }
-        it { is_expected.to be_a Array }
-        it { is_expected.to match_array(tags_from_strings(%w[1 2 3])) }
+        it { expect { subject }.to raise_error(GitHubChangelogGenerator::ChangelogGeneratorError) }
       end
     end
 
     context "with empty array" do
       subject { generator.filter_since_tag(tags_from_strings(%w[])) }
 
-      context "with valid since tag" do
-        let(:generator) { GitHubChangelogGenerator::Generator.new(since_tag: "2") }
-        it { is_expected.to be_a Array }
-        it { is_expected.to match_array(tags_from_strings(%w[])) }
-      end
-
       context "with invalid since tag" do
         let(:generator) { GitHubChangelogGenerator::Generator.new(since_tag: "Invalid tag") }
-        it { is_expected.to be_a Array }
-        it { is_expected.to match_array(tags_from_strings(%w[])) }
+        it { expect { subject }.to raise_error(GitHubChangelogGenerator::ChangelogGeneratorError) }
       end
     end
   end
@@ -225,24 +217,16 @@ def tags_from_strings(tags_strings)
 
       context "with invalid due tag" do
         let(:generator) { GitHubChangelogGenerator::Generator.new(due_tag: "Invalid tag") }
-        it { is_expected.to be_a Array }
-        it { is_expected.to match_array(tags_from_strings(%w[1 2 3])) }
+        it { expect { subject }.to raise_error(GitHubChangelogGenerator::ChangelogGeneratorError) }
       end
     end
 
     context "with empty array" do
       subject { generator.filter_due_tag(tags_from_strings(%w[])) }
 
-      context "with valid due tag" do
-        let(:generator) { GitHubChangelogGenerator::Generator.new(due_tag: "2") }
-        it { is_expected.to be_a Array }
-        it { is_expected.to match_array(tags_from_strings(%w[])) }
-      end
-
       context "with invalid due tag" do
         let(:generator) { GitHubChangelogGenerator::Generator.new(due_tag: "Invalid tag") }
-        it { is_expected.to be_a Array }
-        it { is_expected.to match_array(tags_from_strings(%w[])) }
+        it { expect { subject }.to raise_error(GitHubChangelogGenerator::ChangelogGeneratorError) }
       end
     end
   end