diff --git a/src/index.js b/src/index.js
index 7a8a2f6981..b91cf7231d 100644
--- a/src/index.js
+++ b/src/index.js
@@ -98,6 +98,8 @@ export {
   isWrappingType,
   isNullableType,
   isNamedType,
+  isRequiredArgument,
+  isRequiredInputField,
   isSpecifiedScalarType,
   isIntrospectionType,
   isSpecifiedDirective,
diff --git a/src/type/definition.js b/src/type/definition.js
index bf5e5449fb..952e59bdd9 100644
--- a/src/type/definition.js
+++ b/src/type/definition.js
@@ -858,6 +858,10 @@ export type GraphQLArgument = {
   astNode?: ?InputValueDefinitionNode,
 };
 
+export function isRequiredArgument(arg: GraphQLArgument): boolean %checks {
+  return isNonNullType(arg.type) && arg.defaultValue === undefined;
+}
+
 export type GraphQLFieldMap<TSource, TContext> = ObjMap<
   GraphQLField<TSource, TContext>,
 >;
@@ -1273,4 +1277,10 @@ export type GraphQLInputField = {
   astNode?: ?InputValueDefinitionNode,
 };
 
+export function isRequiredInputField(
+  field: GraphQLInputField,
+): boolean %checks {
+  return isNonNullType(field.type) && field.defaultValue === undefined;
+}
+
 export type GraphQLInputFieldMap = ObjMap<GraphQLInputField>;
diff --git a/src/type/index.js b/src/type/index.js
index e8ac7437ae..4868543ab9 100644
--- a/src/type/index.js
+++ b/src/type/index.js
@@ -35,6 +35,8 @@ export {
   isWrappingType,
   isNullableType,
   isNamedType,
+  isRequiredArgument,
+  isRequiredInputField,
   // Assertions
   assertType,
   assertScalarType,
diff --git a/src/validation/rules/ProvidedRequiredArguments.js b/src/validation/rules/ProvidedRequiredArguments.js
index 8b101adc1e..b140059743 100644
--- a/src/validation/rules/ProvidedRequiredArguments.js
+++ b/src/validation/rules/ProvidedRequiredArguments.js
@@ -11,7 +11,7 @@ import type { ValidationContext } from '../ValidationContext';
 import { GraphQLError } from '../../error/GraphQLError';
 import inspect from '../../jsutils/inspect';
 import keyMap from '../../jsutils/keyMap';
-import { isNonNullType } from '../../type/definition';
+import { isRequiredArgument } from '../../type/definition';
 import type { ASTVisitor } from '../../language/visitor';
 
 export function missingFieldArgMessage(
@@ -58,11 +58,7 @@ export function ProvidedRequiredArguments(
         const argNodeMap = keyMap(argNodes, arg => arg.name.value);
         for (const argDef of fieldDef.args) {
           const argNode = argNodeMap[argDef.name];
-          if (
-            !argNode &&
-            isNonNullType(argDef.type) &&
-            argDef.defaultValue === undefined
-          ) {
+          if (!argNode && isRequiredArgument(argDef)) {
             context.reportError(
               new GraphQLError(
                 missingFieldArgMessage(
@@ -90,11 +86,7 @@ export function ProvidedRequiredArguments(
         const argNodeMap = keyMap(argNodes, arg => arg.name.value);
         for (const argDef of directiveDef.args) {
           const argNode = argNodeMap[argDef.name];
-          if (
-            !argNode &&
-            isNonNullType(argDef.type) &&
-            argDef.defaultValue === undefined
-          ) {
+          if (!argNode && isRequiredArgument(argDef)) {
             context.reportError(
               new GraphQLError(
                 missingDirectiveArgMessage(
diff --git a/src/validation/rules/ValuesOfCorrectType.js b/src/validation/rules/ValuesOfCorrectType.js
index 44e4fdf772..8df1358301 100644
--- a/src/validation/rules/ValuesOfCorrectType.js
+++ b/src/validation/rules/ValuesOfCorrectType.js
@@ -18,6 +18,7 @@ import {
   isInputObjectType,
   isListType,
   isNonNullType,
+  isRequiredInputField,
   getNullableType,
   getNamedType,
 } from '../../type/definition';
@@ -97,16 +98,12 @@ export function ValuesOfCorrectType(context: ValidationContext): ASTVisitor {
       const fieldNodeMap = keyMap(node.fields, field => field.name.value);
       for (const fieldName of Object.keys(inputFields)) {
         const fieldDef = inputFields[fieldName];
-        const fieldType = fieldDef.type;
         const fieldNode = fieldNodeMap[fieldName];
-        if (
-          !fieldNode &&
-          isNonNullType(fieldType) &&
-          fieldDef.defaultValue === undefined
-        ) {
+        if (!fieldNode && isRequiredInputField(fieldDef)) {
+          const typeStr = inspect(fieldDef.type);
           context.reportError(
             new GraphQLError(
-              requiredFieldMessage(type.name, fieldName, inspect(fieldType)),
+              requiredFieldMessage(type.name, fieldName, typeStr),
               node,
             ),
           );