diff --git a/src/Microsoft.ML.Transforms/OneHotHashEncoding.cs b/src/Microsoft.ML.Transforms/OneHotHashEncoding.cs
index aca4ee8802..8b082310da 100644
--- a/src/Microsoft.ML.Transforms/OneHotHashEncoding.cs
+++ b/src/Microsoft.ML.Transforms/OneHotHashEncoding.cs
@@ -180,8 +180,10 @@ internal static IDataTransform Create(IHostEnvironment env, Arguments args, IDat
 
         internal OneHotHashEncoding(HashingEstimator hash, IEstimator<ITransformer> keyToVector, IDataView input)
         {
-            var chain = hash.Append(keyToVector);
-            _transformer = chain.Fit(input);
+            if (keyToVector != null)
+                _transformer = hash.Append(keyToVector).Fit(input);
+            else
+                _transformer = new TransformerChain<ITransformer>(hash.Fit(input));
         }
 
         public Schema GetOutputSchema(Schema inputSchema) => _transformer.GetOutputSchema(inputSchema);