diff --git a/lib/FredyRuntime.js b/lib/FredyRuntime.js
index 7693916..0b358f2 100755
--- a/lib/FredyRuntime.js
+++ b/lib/FredyRuntime.js
@@ -107,7 +107,7 @@ class FredyRuntime {
       }
       return !similar;
     });
-    filteredList.forEach((filter) => this._similarityCache.addCacheEntry(filter.title, listings.address));
+    filteredList.forEach((filter) => this._similarityCache.addCacheEntry(filter.title, filter.address));
     return filteredList;
   }
 
diff --git a/test/FredyRuntime/FredyRuntime.test.js b/test/FredyRuntime/FredyRuntime.test.js
new file mode 100644
index 0000000..89817d0
--- /dev/null
+++ b/test/FredyRuntime/FredyRuntime.test.js
@@ -0,0 +1,53 @@
+import { expect } from 'chai';
+import * as similarityCache from '../../lib/services/similarity-check/similarityCache.js';
+import { mockFredy } from '../utils.js';
+
+describe('FredyRuntime', () => {
+  afterEach(() => {
+    similarityCache.invalidateAllForTest();
+  });
+
+  after(() => {
+    similarityCache.stopCacheCleanup();
+  });
+
+  describe('_filterBySimilarListings', () => {
+    let fredyRuntime;
+
+    beforeEach(async () => {
+      const FredyRuntime = await mockFredy();
+      fredyRuntime = new FredyRuntime({}, null, 'dummy-provider', 'dummy-job', similarityCache);
+    });
+
+    it('should filter out listings with similar title and address already in cache', () => {
+      similarityCache.addCacheEntry('Penthouse', 'Mustermann Straße 1');
+
+      const listings = [
+        { id: '1', title: 'Penthouse', address: 'Mustermann Straße 1' },
+        { id: '2', title: 'Nice apartment', address: 'Mustermann Straße 15' },
+      ];
+
+      const result = fredyRuntime._filterBySimilarListings(listings);
+
+      expect(result).to.have.length(1);
+      expect(result[0].id).to.equal('2');
+      expect(result[0].title).to.equal('Nice apartment');
+
+      expect(similarityCache.hasSimilarEntries('Nice apartment', 'Mustermann Straße 15')).to.be.true;
+    });
+
+    it('should handle listings with null or undefined address', () => {
+      const listings = [
+        { id: '1', title: 'Penthouse', address: null },
+        { id: '2', title: 'Nice apartment', address: undefined },
+      ];
+
+      const result = fredyRuntime._filterBySimilarListings(listings);
+
+      expect(result).to.have.length(2);
+
+      expect(similarityCache.hasSimilarEntries('Penthouse', null)).to.be.true;
+      expect(similarityCache.hasSimilarEntries('Nice apartment', undefined)).to.be.true;
+    });
+  });
+});