diff --git a/gfx/layers/apz/testutil/APZTestData.h b/gfx/layers/apz/testutil/APZTestData.h
index b94974effa7..127300b5b72 100644
--- a/gfx/layers/apz/testutil/APZTestData.h
+++ b/gfx/layers/apz/testutil/APZTestData.h
@@ -42,13 +42,10 @@ class APZTestData {
   friend class APZTestDataToJSConverter;
 public:
   void StartNewPaint(SequenceNumber aSequenceNumber) {
-    auto insertResult = mPaints.insert(DataStore::value_type(aSequenceNumber, Bucket()));
-    if (!insertResult.second) {
-      // TODO(botond): Change this to MOZ_ASSERT once we get rid of
-      // APZCTreeManager::UpdatePanZoomControllerTree() calls for repeat
-      // transactions.
-      NS_WARNING("Already have a paint with this sequence number");
-    }
+    mPaints.insert(DataStore::value_type(aSequenceNumber, Bucket()));
+    // TODO(botond): MOZ_ASSERT() that we didn't already have a paint with this
+    // sequence number once we get rid ofAPZCTreeManager::UpdatePanZoomControllerTree()
+    // calls for repeat transactions (bug 1007728).
   }
   void LogTestDataForPaint(SequenceNumber aSequenceNumber,
                            ViewID aScrollId,
@@ -96,13 +93,10 @@ private:
     }
     Bucket& bucket = bucketIterator->second;
     ScrollFrameData& scrollFrameData = bucket[aScrollId];  // create if doesn't exist
-    auto insertResult = scrollFrameData.insert(ScrollFrameData::value_type(aKey, aValue));
-    if (!insertResult.second) {
-      // TODO(botond): Change this to MOZ_ASSERT once we get rid of
-      // APZCTreeManager::UpdatePanZoomControllerTree() calls for repeat
-      // transactions.
-      NS_WARNING("Key already present in test data, not overwriting");
-    }
+    scrollFrameData.insert(ScrollFrameData::value_type(aKey, aValue));
+    // TODO(botond): MOZ_ASSERT() that we don't already have this key once we
+    // get rid of APZCTreeManager::UpdatePanZoomControllerTree() calls for
+    // repeat transactions (bug 1007728).
   }
 };