diff --git a/src/main/java/graphql/execution/ExecutionStrategy.java b/src/main/java/graphql/execution/ExecutionStrategy.java
index 41d80eccf1..2286192afd 100644
--- a/src/main/java/graphql/execution/ExecutionStrategy.java
+++ b/src/main/java/graphql/execution/ExecutionStrategy.java
@@ -349,21 +349,21 @@ protected <T> CompletableFuture<T> handleFetchingException(ExecutionContext exec
                 .build();
 
         try {
-            return asyncHandleException(dataFetcherExceptionHandler, handlerParameters, executionContext);
+            return asyncHandleException(dataFetcherExceptionHandler, handlerParameters);
         } catch (Exception handlerException) {
             handlerParameters = DataFetcherExceptionHandlerParameters.newExceptionParameters()
                     .dataFetchingEnvironment(environment)
                     .exception(handlerException)
                     .build();
-            return asyncHandleException(new SimpleDataFetcherExceptionHandler(), handlerParameters, executionContext);
+            return asyncHandleException(new SimpleDataFetcherExceptionHandler(), handlerParameters);
         }
     }
 
-    private <T> CompletableFuture<T> asyncHandleException(DataFetcherExceptionHandler handler, DataFetcherExceptionHandlerParameters handlerParameters, ExecutionContext executionContext) {
+    private <T> CompletableFuture<T> asyncHandleException(DataFetcherExceptionHandler handler, DataFetcherExceptionHandlerParameters handlerParameters) {
         //noinspection unchecked
-        return handler.handleException(handlerParameters)
-                .thenApply(handlerResult -> (T) DataFetcherResult.<FetchedValue>newResult().errors(handlerResult.getErrors()).build()
-                );
+        return handler.handleException(handlerParameters).thenApply(
+                handlerResult -> (T) DataFetcherResult.<FetchedValue>newResult().errors(handlerResult.getErrors()).build()
+        );
     }
 
     /**
@@ -620,7 +620,7 @@ protected CompletableFuture<ExecutionResult> completeValueForScalar(ExecutionCon
     protected CompletableFuture<ExecutionResult> completeValueForEnum(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLEnumType enumType, Object result) {
         Object serialized;
         try {
-            serialized = enumType.serialize(result);
+            serialized = enumType.serialize(result, executionContext.getGraphQLContext(), executionContext.getLocale());
         } catch (CoercingSerializeException e) {
             serialized = handleCoercionProblem(executionContext, parameters, e);
         }
@@ -633,7 +633,7 @@ protected CompletableFuture<ExecutionResult> completeValueForEnum(ExecutionConte
     }
 
     /**
-     * Called to turn an java object value into an graphql object value
+     * Called to turn a java object value into an graphql object value
      *
      * @param executionContext   contains the top level execution parameters
      * @param parameters         contains the parameters holding the fields to be executed and source object
@@ -649,7 +649,7 @@ protected CompletableFuture<ExecutionResult> completeValueForObject(ExecutionCon
                 .schema(executionContext.getGraphQLSchema())
                 .objectType(resolvedObjectType)
                 .fragments(executionContext.getFragmentsByName())
-                .variables(executionContext.getVariables())
+                .variables(executionContext.getCoercedVariables().toMap())
                 .build();
 
         MergedSelectionSet subFields = fieldCollector.collectFields(collectorParameters, parameters.getField());
@@ -679,7 +679,6 @@ private Object handleCoercionProblem(ExecutionContext context, ExecutionStrategy
         return null;
     }
 
-
     /**
      * Converts an object that is known to should be an Iterable into one
      *
@@ -694,6 +693,10 @@ protected Iterable<Object> toIterable(Object result) {
     }
 
     protected GraphQLObjectType resolveType(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLType fieldType) {
+        // we can avoid a method call and type resolver environment allocation if we know it's an object type
+        if (fieldType instanceof GraphQLObjectType) {
+            return (GraphQLObjectType) fieldType;
+        }
         return resolvedType.resolveType(executionContext, parameters.getField(), parameters.getSource(), parameters.getExecutionStepInfo(), fieldType, parameters.getLocalContext());
     }
 
@@ -743,7 +746,7 @@ protected GraphQLFieldDefinition getFieldDef(GraphQLSchema schema, GraphQLObject
     }
 
     /**
-     * See (http://facebook.github.io/graphql/#sec-Errors-and-Non-Nullability),
+     * See (<a href="http://facebook.github.io/graphql/#sec-Errors-and-Non-Nullability">...</a>),
      * <p>
      * If a non nullable child field type actually resolves to a null value and the parent type is nullable
      * then the parent must in fact become null
diff --git a/src/main/java/graphql/execution/ResolveType.java b/src/main/java/graphql/execution/ResolveType.java
index fbc9b5f536..3ef9c556fb 100644
--- a/src/main/java/graphql/execution/ResolveType.java
+++ b/src/main/java/graphql/execution/ResolveType.java
@@ -1,5 +1,6 @@
 package graphql.execution;
 
+import graphql.Assert;
 import graphql.Internal;
 import graphql.TypeResolutionEnvironment;
 import graphql.normalized.ExecutableNormalizedField;
@@ -19,9 +20,9 @@
 @Internal
 public class ResolveType {
 
-
     public GraphQLObjectType resolveType(ExecutionContext executionContext, MergedField field, Object source, ExecutionStepInfo executionStepInfo, GraphQLType fieldType, Object localContext) {
-        GraphQLObjectType resolvedType;
+        Assert.assertTrue(fieldType instanceof GraphQLInterfaceType || fieldType instanceof GraphQLUnionType,
+                () -> "The passed in fieldType MUST be an interface or union type : " + fieldType.getClass().getName());
         DataFetchingFieldSelectionSet fieldSelectionSet = buildSelectionSet(executionContext, field, (GraphQLOutputType) fieldType, executionStepInfo);
         TypeResolutionEnvironment env = TypeResolutionParameters.newParameters()
                 .field(field)
@@ -35,13 +36,10 @@ public GraphQLObjectType resolveType(ExecutionContext executionContext, MergedFi
                 .schema(executionContext.getGraphQLSchema())
                 .build();
         if (fieldType instanceof GraphQLInterfaceType) {
-            resolvedType = resolveTypeForInterface(env, (GraphQLInterfaceType) fieldType);
-        } else if (fieldType instanceof GraphQLUnionType) {
-            resolvedType = resolveTypeForUnion(env, (GraphQLUnionType) fieldType);
+            return resolveTypeForInterface(env, (GraphQLInterfaceType) fieldType);
         } else {
-            resolvedType = (GraphQLObjectType) fieldType;
+            return resolveTypeForUnion(env, (GraphQLUnionType) fieldType);
         }
-        return resolvedType;
     }
 
     private DataFetchingFieldSelectionSet buildSelectionSet(ExecutionContext executionContext, MergedField field, GraphQLOutputType fieldType, ExecutionStepInfo executionStepInfo) {
@@ -65,11 +63,9 @@ private GraphQLObjectType resolveAbstractType(TypeResolutionEnvironment env, Typ
         if (result == null) {
             throw new UnresolvedTypeException(abstractType);
         }
-
         if (!env.getSchema().isPossibleType(abstractType, result)) {
             throw new UnresolvedTypeException(abstractType, result);
         }
-
         return result;
     }