diff --git a/src/Microsoft.AspNet.Mvc.Core/ModelBinding/CompositeModelBinder.cs b/src/Microsoft.AspNet.Mvc.Core/ModelBinding/CompositeModelBinder.cs
index 7efc8abfa9..26d4f227d8 100644
--- a/src/Microsoft.AspNet.Mvc.Core/ModelBinding/CompositeModelBinder.cs
+++ b/src/Microsoft.AspNet.Mvc.Core/ModelBinding/CompositeModelBinder.cs
@@ -23,18 +23,18 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
         /// Initializes a new instance of the CompositeModelBinder class.
         /// </summary>
         /// <param name="modelBinders">A collection of <see cref="IModelBinder"/> instances.</param>
-        public CompositeModelBinder(IEnumerable<IModelBinder> modelBinders)
+        public CompositeModelBinder(IList<IModelBinder> modelBinders)
         {
             if (modelBinders == null)
             {
                 throw new ArgumentNullException(nameof(modelBinders));
             }
 
-            ModelBinders = new List<IModelBinder>(modelBinders);
+            ModelBinders = modelBinders;
         }
 
         /// <inheritdoc />
-        public IReadOnlyList<IModelBinder> ModelBinders { get; }
+        public IList<IModelBinder> ModelBinders { get; }
 
         public virtual Task<ModelBindingResult> BindModelAsync(ModelBindingContext bindingContext)
         {
diff --git a/src/Microsoft.AspNet.Mvc.Core/ModelBinding/Validation/CompositeModelValidatorProvider.cs b/src/Microsoft.AspNet.Mvc.Core/ModelBinding/Validation/CompositeModelValidatorProvider.cs
index f43bea00ae..8e65c8e38c 100644
--- a/src/Microsoft.AspNet.Mvc.Core/ModelBinding/Validation/CompositeModelValidatorProvider.cs
+++ b/src/Microsoft.AspNet.Mvc.Core/ModelBinding/Validation/CompositeModelValidatorProvider.cs
@@ -17,20 +17,20 @@ namespace Microsoft.AspNet.Mvc.ModelBinding.Validation
         /// <param name="providers">
         /// A collection of <see cref="IModelValidatorProvider"/> instances.
         /// </param>
-        public CompositeModelValidatorProvider(IEnumerable<IModelValidatorProvider> providers)
+        public CompositeModelValidatorProvider(IList<IModelValidatorProvider> providers)
         {
             if (providers == null)
             {
                 throw new ArgumentNullException(nameof(providers));
             }
 
-            ValidatorProviders = new List<IModelValidatorProvider>(providers);
+            ValidatorProviders = providers;
         }
 
         /// <summary>
         /// Gets the list of <see cref="IModelValidatorProvider"/> instances.
         /// </summary>
-        public IReadOnlyList<IModelValidatorProvider> ValidatorProviders { get; }
+        public IList<IModelValidatorProvider> ValidatorProviders { get; }
 
         /// <inheritdoc />
         public void GetValidators(ModelValidatorProviderContext context)
diff --git a/test/Microsoft.AspNet.Mvc.TestCommon/TestModelValidatorProvider.cs b/test/Microsoft.AspNet.Mvc.TestCommon/TestModelValidatorProvider.cs
index 906a5f7f10..9f347ec3eb 100644
--- a/test/Microsoft.AspNet.Mvc.TestCommon/TestModelValidatorProvider.cs
+++ b/test/Microsoft.AspNet.Mvc.TestCommon/TestModelValidatorProvider.cs
@@ -21,7 +21,7 @@ namespace Microsoft.AspNet.Mvc.ModelBinding.Validation
             return new TestModelValidatorProvider(providers);
         }
 
-        public TestModelValidatorProvider(IEnumerable<IModelValidatorProvider> providers)
+        public TestModelValidatorProvider(IList<IModelValidatorProvider> providers)
             : base(providers)
         {
         }