diff --git a/lib/messages/search_response.js b/lib/messages/search_response.js
index c9d88c62..2ac5163d 100644
--- a/lib/messages/search_response.js
+++ b/lib/messages/search_response.js
@@ -21,7 +21,7 @@ class SearchResponse extends SearchResultDone {
   constructor (options = {}) {
     super(options)
 
-    this.attributes = options.attributes ? options.attributes.slice() : []
+    this.attributes = options.attributes ? options.attributes.slice().map(a => a.toLowerCase()) : []
     this.notAttributes = []
     this.sentEntries = 0
   }
diff --git a/test/issue-900.test.js b/test/issue-900.test.js
new file mode 100644
index 00000000..979b0228
--- /dev/null
+++ b/test/issue-900.test.js
@@ -0,0 +1,165 @@
+'use strict'
+
+const tap = require('tap')
+const ldapjs = require('../')
+
+const server = ldapjs.createServer()
+
+const SUFFIX = ''
+const directory = {
+  'dc=example,dc=com': {
+    objectclass: 'example',
+    dc: 'example',
+    cn: 'example'
+  },
+  'cn=foo,dc=example,dc=com': {
+    objectclass: 'example',
+    dn: 'cn=foo,dc=example,dc=com',
+    cn: 'foo',
+    lowercase: 'r-1',
+    UPPERCASE: 'r-2',
+    miXed: 'r-3'
+  }
+}
+
+server.bind(SUFFIX, (req, res, done) => {
+  res.end()
+  return done()
+})
+
+server.search(SUFFIX, (req, res, done) => {
+  const dn = req.dn.toString().toLowerCase()
+
+  if (Object.hasOwn(directory, dn) === false) {
+    return done(Error('not in directory'))
+  }
+
+  res.send({
+    dn,
+    attributes: directory[dn]
+  })
+
+  res.end()
+  done()
+})
+
+tap.beforeEach(t => {
+  return new Promise((resolve, reject) => {
+    server.listen(0, '127.0.0.1', (err) => {
+      if (err) return reject(err)
+      t.context.url = server.url
+
+      t.context.client = ldapjs.createClient({ url: [server.url] })
+      t.context.searchOpts = {
+        filter: '(&(objectClass=*))',
+        scope: 'sub'
+      }
+
+      resolve()
+    })
+  })
+})
+
+tap.afterEach(t => {
+  return new Promise((resolve, reject) => {
+    t.context.client.destroy()
+    server.close((err) => {
+      if (err) return reject(err)
+      resolve()
+    })
+  })
+})
+
+tap.test('returns lowercase attribute', t => {
+  const { client, searchOpts } = t.context
+
+  client.search('cn=foo,dc=example,dc=com', {
+    ...searchOpts,
+    attributes: ['lowercase']
+  }, (err, res) => {
+    t.error(err)
+    res.on('searchEntry', e => {
+      t.equal(e.pojo.attributes.length, 1)
+      t.match(e.pojo.attributes[0],
+        {
+          type: 'lowercase',
+          values: ['r-1']
+        }
+      )
+
+      t.end()
+    })
+  })
+
+  tap.test('returns UPPERCASE attribute', t => {
+    const { client, searchOpts } = t.context
+
+    client.search('cn=foo,dc=example,dc=com', {
+      ...searchOpts,
+      attributes: ['UPPERCASE']
+    }, (err, res) => {
+      t.error(err)
+      res.on('searchEntry', e => {
+        t.equal(e.pojo.attributes.length, 1)
+        t.match(e.pojo.attributes[0],
+          {
+            type: 'UPPERCASE',
+            values: ['r-2']
+          }
+        )
+
+        t.end()
+      })
+    })
+  })
+
+  tap.test('returns miXed attribute', t => {
+    const { client, searchOpts } = t.context
+
+    client.search('cn=foo,dc=example,dc=com', {
+      ...searchOpts,
+      attributes: ['miXed']
+    }, (err, res) => {
+      t.error(err)
+      res.on('searchEntry', e => {
+        t.equal(e.pojo.attributes.length, 1)
+        t.match(e.pojo.attributes[0],
+          {
+            type: 'miXed',
+            values: ['r-3']
+          }
+        )
+
+        t.end()
+      })
+    })
+  })
+
+  tap.test('uses insensitive attribute matching', t => {
+    const { client, searchOpts } = t.context
+
+    client.search('cn=foo,dc=example,dc=com', {
+      ...searchOpts,
+      attributes: ['uppercase', 'mixed']
+    }, (err, res) => {
+      t.error(err)
+      res.on('searchEntry', e => {
+        t.equal(e.pojo.attributes.length, 2)
+        t.match(e.pojo.attributes.find(a => a.type === 'UPPERCASE'),
+          {
+            type: 'UPPERCASE',
+            values: ['r-2']
+          }
+        )
+        t.match(e.pojo.attributes.find(a => a.type === 'miXed'),
+          {
+            type: 'miXed',
+            values: ['r-3']
+          }
+        )
+
+        t.end()
+      })
+    })
+  })
+})