diff --git a/src/action.ts b/src/action.ts
index 16e381d0..dbc0ee01 100644
--- a/src/action.ts
+++ b/src/action.ts
@@ -110,11 +110,9 @@ export default async function main() {
 
     commits = await getCommits(previousTag.commit.sha, GITHUB_SHA);
 
-    const releaseRules =
-      mappedReleaseRules &&
-      mappedReleaseRules.map(
-        (rule) => objectWithoutKeys(rule, ['section']) as ReleaseRule
-      );
+    const releaseRules = mappedReleaseRules?.map(
+      (rule) => objectWithoutKeys(rule, ['section']) as ReleaseRule
+    );
     let bump = await analyzeCommits(
       { releaseRules },
       { commits, logger: { log: console.info.bind(console) } }
diff --git a/src/ts.ts b/src/ts.ts
index d094a22a..a3034bfa 100644
--- a/src/ts.ts
+++ b/src/ts.ts
@@ -30,5 +30,5 @@ export type ChangelogRule = {
    * Section in changelog to group commits by type.
    * Eg: 'Bug Fix', 'Features' etc.
    */
-  section: string;
+  section?: string;
 };
diff --git a/tests/utils.test.ts b/tests/utils.test.ts
index bfec2859..73f5cbf2 100644
--- a/tests/utils.test.ts
+++ b/tests/utils.test.ts
@@ -2,6 +2,7 @@ import * as utils from '../src/utils';
 import { getValidTags } from '../src/utils';
 import * as core from '@actions/core';
 import * as github from '../src/github';
+import { defaultChangelogRules } from '../src/defaults';
 
 jest.spyOn(core, 'debug').mockImplementation(() => {});
 jest.spyOn(core, 'warning').mockImplementation(() => {});
@@ -140,7 +141,8 @@ describe('utils', () => {
       /*
        * Given
        */
-      const customReleasesString = 'james:preminor,bond:premajor';
+      const customReleasesString =
+        'james:preminor,bond:premajor,007:major:Breaking Changes,feat:minor';
 
       /*
        * When
@@ -153,6 +155,12 @@ describe('utils', () => {
       expect(mappedReleases).toEqual([
         { type: 'james', release: 'preminor' },
         { type: 'bond', release: 'premajor' },
+        { type: '007', release: 'major', section: 'Breaking Changes' },
+        {
+          type: 'feat',
+          release: 'minor',
+          section: defaultChangelogRules['feat'].section,
+        },
       ]);
     });
 
@@ -173,4 +181,73 @@ describe('utils', () => {
       expect(mappedReleases).toEqual([{ type: 'bond', release: 'premajor' }]);
     });
   });
+
+  describe('method: mergeWithDefaultChangelogRules', () => {
+    it('combines non-existing type rules with default rules', () => {
+      /**
+       * Given
+       */
+      const newRule = {
+        type: 'james',
+        release: 'major',
+        section: '007 Changes',
+      };
+
+      /**
+       * When
+       */
+      const result = utils.mergeWithDefaultChangelogRules([newRule]);
+
+      /**
+       * Then
+       */
+      expect(result).toEqual([
+        ...Object.values(defaultChangelogRules),
+        newRule,
+      ]);
+    });
+
+    it('overwrites existing default type rules with provided rules', () => {
+      /**
+       * Given
+       */
+      const newRule = {
+        type: 'feat',
+        release: 'minor',
+        section: '007 Changes',
+      };
+
+      /**
+       * When
+       */
+      const result = utils.mergeWithDefaultChangelogRules([newRule]);
+      const overWrittenRule = result.find((rule) => rule.type === 'feat');
+
+      /**
+       * Then
+       */
+      expect(overWrittenRule?.section).toBe(newRule.section);
+    });
+
+    it('returns only the rules having changelog section', () => {
+      /**
+       * Given
+       */
+      const mappedReleaseRules = [
+        { type: 'james', release: 'major', section: '007 Changes' },
+        { type: 'bond', release: 'minor', section: undefined },
+      ];
+
+      /**
+       * When
+       */
+      const result = utils.mergeWithDefaultChangelogRules(mappedReleaseRules);
+
+      /**
+       * Then
+       */
+      expect(result).toContainEqual(mappedReleaseRules[0]);
+      expect(result).not.toContainEqual(mappedReleaseRules[1]);
+    });
+  });
 });