diff --git a/lib/relations/RelationOwner.js b/lib/relations/RelationOwner.js
index 53adb57bb..847637a6f 100644
--- a/lib/relations/RelationOwner.js
+++ b/lib/relations/RelationOwner.js
@@ -219,7 +219,7 @@ function containsNonNull(arr) {
 }
 
 function join(id) {
-  return id.join(',');
+  return id.map(x => (Buffer.isBuffer(x) ? x.toString('hex') : x)).join(',');
 }
 
 function isIdProp(relationProp) {
diff --git a/tests/integration/misc/#1627.js b/tests/integration/misc/#1627.js
index 3bd080e67..14643a6d4 100644
--- a/tests/integration/misc/#1627.js
+++ b/tests/integration/misc/#1627.js
@@ -90,5 +90,21 @@ module.exports = session => {
 
       expect(result).to.eql(inserted);
     });
+    it('should fetch multiple relations correctly', async () => {
+      const ids = [
+        Buffer.from('00000000000000000000000000007AAC', 'hex'),
+        Buffer.from('00000000000000000000000000007AAD', 'hex'),
+        Buffer.from('00000000000000000000000000007AAE', 'hex')
+      ];
+      const graph = ids.map(id => ({
+        id,
+        roles: [{ id: crypto.randomBytes(16) }]
+      }));
+      const inserted = await User.query().insertGraph(graph);
+      const result = await User.query()
+        .findByIds(ids)
+        .withGraphFetched('roles');
+      expect(result).to.eql(inserted);
+    });
   });
 };
diff --git a/tests/unit/utils.js b/tests/unit/utils.js
index f8468783c..f509d4f4d 100644
--- a/tests/unit/utils.js
+++ b/tests/unit/utils.js
@@ -12,7 +12,7 @@ const {
 const { range } = require('lodash');
 const { compose, mixin } = require('../../lib/utils/mixin');
 const { map } = require('../../lib/utils/promiseUtils');
-const { jsonEquals } = require('../../lib/utils/objectUtils');
+const { jsonEquals, uniqBy } = require('../../lib/utils/objectUtils');
 
 describe('utils', () => {
   describe('mixin', () => {
@@ -428,4 +428,22 @@ describe('utils', () => {
       ).to.equal(false);
     });
   });
+  describe('uniqBy', () => {
+    const items = [
+      [Buffer.from('00000000000000000000000000007AAD', 'hex')],
+      [Buffer.from('00000000000000000000000000007AAE', 'hex')],
+      [Buffer.from('00000000000000000000000000007AAC', 'hex')]
+    ];
+    it('should work with Buffer items', () => {
+      expect(uniqBy(items)).to.eql(items);
+    });
+    it('should work with Buffer[] items', () => {
+      expect(uniqBy(items)).to.eql(items);
+    });
+    it('should work with Buffer[] items with custom keyGetter function', () => {
+      expect(
+        uniqBy(items, item => item.map(x => (Buffer.isBuffer(x) ? x.toString('hex') : x)).join(','))
+      ).to.eql(items);
+    });
+  });
 });