diff --git a/src/Microsoft.ML.FastTree/TreeEnsemble/TreeEnsembleCombiner.cs b/src/Microsoft.ML.FastTree/TreeEnsemble/TreeEnsembleCombiner.cs
index b938ee3f5b..93258ea7c7 100644
--- a/src/Microsoft.ML.FastTree/TreeEnsemble/TreeEnsembleCombiner.cs
+++ b/src/Microsoft.ML.FastTree/TreeEnsemble/TreeEnsembleCombiner.cs
@@ -65,9 +65,9 @@ IPredictor IModelCombiner.CombineModels(IEnumerable<IPredictor> models)
                 foreach (var t in tree.TrainedEnsemble.Trees)
                 {
                     var bytes = new byte[t.SizeInBytes()];
-                    int position = -1;
+                    int position = 0;
                     t.ToByteArray(bytes, ref position);
-                    position = -1;
+                    position = 0;
                     var tNew = new InternalRegressionTree(bytes, ref position);
                     if (paramA != 1)
                     {
diff --git a/test/Microsoft.ML.Predictor.Tests/TestPredictors.cs b/test/Microsoft.ML.Predictor.Tests/TestPredictors.cs
index f7abc2fc1f..89ac4b6e2d 100644
--- a/test/Microsoft.ML.Predictor.Tests/TestPredictors.cs
+++ b/test/Microsoft.ML.Predictor.Tests/TestPredictors.cs
@@ -625,7 +625,7 @@ public void RankingLightGBMTest()
             Done();
         }
 
-        [X64Fact("x86 fails. Associated GitHubIssue: https://github.com/dotnet/machinelearning/issues/1216")]
+        [Fact]
         public void TestTreeEnsembleCombiner()
         {
             var dataPath = GetDataPath("breast-cancer.txt");
@@ -646,7 +646,7 @@ public void TestTreeEnsembleCombiner()
             CombineAndTestTreeEnsembles(dataView, fastTrees);
         }
 
-        [X64Fact("x86 fails. Associated GitHubIssue: https://github.com/dotnet/machinelearning/issues/1216")]
+        [Fact]
         public void TestTreeEnsembleCombinerWithCategoricalSplits()
         {
             var dataPath = GetDataPath("adult.tiny.with-schema.txt");
@@ -755,7 +755,7 @@ private void CombineAndTestTreeEnsembles(IDataView idv, PredictorModel[] fastTre
             }
         }
 
-        [X64Fact("x86 fails. Associated GitHubIssue: https://github.com/dotnet/machinelearning/issues/1216")]
+        [Fact]
         public void TestEnsembleCombiner()
         {
             var dataPath = GetDataPath("breast-cancer.txt");
@@ -801,7 +801,7 @@ public void TestEnsembleCombiner()
             Done();
         }
 
-        [X64Fact("x86 fails. Associated GitHubIssue: https://github.com/dotnet/machinelearning/issues/1216")]
+        [LightGBMFact]
         public void TestMulticlassEnsembleCombiner()
         {
             var dataPath = GetDataPath("breast-cancer.txt");