diff --git a/src/MiniSearch.test.js b/src/MiniSearch.test.js
index e7febaf7..936cb074 100644
--- a/src/MiniSearch.test.js
+++ b/src/MiniSearch.test.js
@@ -1159,6 +1159,25 @@ describe('MiniSearch', () => {
       expect(results.every(({ category }) => category === 'poetry')).toBe(true)
     })
 
+    it('allows customizing BM25+ parameters', () => {
+      const ms = new MiniSearch({ fields: ['text'], searchOptions: { _bm25: { k: 1.2, b: 0.7, d: 0.5 } } })
+      const documents = [
+        { id: 1, text: 'something very very very cool' },
+        { id: 2, text: 'something cool' }
+      ]
+      ms.addAll(documents)
+
+      expect(ms.search('very')[0].score).toBeGreaterThan(ms.search('very', { _bm25: { k: 1, b: 0.7, d: 0.5 } })[0].score)
+      expect(ms.search('something')[1].score).toBeGreaterThan(ms.search('something', { _bm25: { k: 1.2, b: 1, d: 0.5 } })[1].score)
+      expect(ms.search('something')[1].score).toBeGreaterThan(ms.search('something', { _bm25: { k: 1.2, b: 0.7, d: 0.1 } })[1].score)
+
+      // Defaults are taken from the searchOptions passed to the constructor
+      const other = new MiniSearch({ fields: ['text'], searchOptions: { _bm25: { k: 1, b: 0.7, d: 0.5 } } })
+      other.addAll(documents)
+
+      expect(other.search('very')).toEqual(ms.search('very', { _bm25: { k: 1, b: 0.7, d: 0.5 } }))
+    })
+
     describe('when passing a query tree', () => {
       it('searches according to the given combination', () => {
         const results = ms.search({
@@ -1514,7 +1533,7 @@ describe('MiniSearch', () => {
         expect(ms.search('queen', { fuzzy: 1, prefix: true })[0].song).toEqual('Killer Queen')
       })
     })
-  })
+  }) 
 
   describe('default tokenization', () => {
     it('splits on non-alphanumeric taking diacritics into account', () => {