--- a/gfx/layers/ipc/CrossProcessCompositorBridgeParent.cpp
+++ b/gfx/layers/ipc/CrossProcessCompositorBridgeParent.cpp
@@ -89,19 +89,17 @@ CrossProcessCompositorBridgeParent::Allo
     sIndirectLayerTrees[aId].mLayerTree = p;
     if (state->mPendingCompositorUpdate) {
       p->SetPendingCompositorUpdate(state->mPendingCompositorUpdate.value());
     }
     return p;
   }
 
   NS_WARNING("Created child without a matching parent?");
-  // XXX: should be false, but that causes us to fail some tests on Mac w/ OMTC.
-  // Bug 900745. change *aSuccess to false to see test failures.
-  *aSuccess = true;
+  *aSuccess = false;
   LayerTransactionParent* p = new LayerTransactionParent(nullptr, this, aId);
   p->AddIPDLReference();
   return p;
 }
 
 bool
 CrossProcessCompositorBridgeParent::DeallocPLayerTransactionParent(PLayerTransactionParent* aLayers)
 {