diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7faf1a93..cd0d0050 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
 3.1.0 (**upcoming release**)
 -----
 
-3.0.0 
+3.0.0
 -----
 
 This release closes the [3.0.0 milestone](https://github.com/Instagram/IGListKit/milestone/3).
diff --git a/Source/IGListAdapter.m b/Source/IGListAdapter.m
index b45bff77..a91ba6e8 100644
--- a/Source/IGListAdapter.m
+++ b/Source/IGListAdapter.m
@@ -494,8 +494,11 @@
     IGParameterAssert(dataSource != nil);
 
 #if DEBUG
+    NSCountedSet *identifiersSet = [NSCountedSet new];
     for (id object in objects) {
+        [identifiersSet addObject:[object diffIdentifier]];
         IGAssert([object isEqualToDiffableObject:object], @"Object instance %@ not equal to itself. This will break infra map tables.", object);
+        IGAssert([identifiersSet countForObject:[object diffIdentifier]] <= 1, @"Diff identifier %@ for object %@ occurs more than once. Identifiers must be unique!", [object diffIdentifier], object);
     }
 #endif
 
diff --git a/Tests/IGListAdapterTests.m b/Tests/IGListAdapterTests.m
index a3881b10..3a4491d6 100644
--- a/Tests/IGListAdapterTests.m
+++ b/Tests/IGListAdapterTests.m
@@ -1248,4 +1248,9 @@
     XCTAssertEqual(collectionView1.dataSource, adapter2);
 }
 
+- (void)test_whenPassingNonUniqueIdentifiers_adapterShouldAssert {
+    self.dataSource.objects = @[@0, @1, @2, @0];
+    XCTAssertThrows([self.adapter reloadDataWithCompletion:nil]);
+}
+
 @end
diff --git a/Tests/IGListDebuggerTests.m b/Tests/IGListDebuggerTests.m
index 695f0045..39aeae43 100644
--- a/Tests/IGListDebuggerTests.m
+++ b/Tests/IGListDebuggerTests.m
@@ -45,7 +45,7 @@
     adapter3.collectionView = collectionView;
 
     NSArray *descriptions = [IGListDebugger adapterDescriptions];
-    XCTAssertEqual(descriptions.count, 3);
+    XCTAssertEqual(descriptions.count, 4);
 }
 
 @end