diff --git a/src/Autofac/Features/OpenGenerics/OpenGenericDecoratorRegistrationSource.cs b/src/Autofac/Features/OpenGenerics/OpenGenericDecoratorRegistrationSource.cs
index 6e0d6e44c..3a3c027be 100644
--- a/src/Autofac/Features/OpenGenerics/OpenGenericDecoratorRegistrationSource.cs
+++ b/src/Autofac/Features/OpenGenerics/OpenGenericDecoratorRegistrationSource.cs
@@ -77,13 +77,20 @@ public IEnumerable<IComponentRegistration> RegistrationsFor(Service service, Fun
             return Enumerable.Empty<IComponentRegistration>();
         }
 
-        private static IEnumerable<Parameter> AddDecoratedComponentParameter(Type decoratedParameterType, IComponentRegistration decoratedComponent, IEnumerable<Parameter> configuredParameters)
+        private static Parameter[] AddDecoratedComponentParameter(Type decoratedParameterType, IComponentRegistration decoratedComponent, IList<Parameter> configuredParameters)
         {
             var parameter = new ResolvedParameter(
                 (pi, c) => pi.ParameterType == decoratedParameterType,
                 (pi, c) => c.ResolveComponent(decoratedComponent, Enumerable.Empty<Parameter>()));
 
-            return new[] { parameter }.Concat(configuredParameters);
+            var resultArray = new Parameter[configuredParameters.Count + 1];
+            resultArray[0] = parameter;
+            for (int i = 0; i < configuredParameters.Count; i++)
+            {
+                resultArray[i + 1] = configuredParameters[i];
+            }
+
+            return resultArray;
         }
 
         public bool IsAdapterForIndividualComponents => true;