diff --git a/src/type/__tests__/introspection-test.ts b/src/type/__tests__/introspection-test.ts
index 9cdfe70697..d5157b9750 100644
--- a/src/type/__tests__/introspection-test.ts
+++ b/src/type/__tests__/introspection-test.ts
@@ -242,9 +242,13 @@ describe('Introspection', () => {
                     {
                       name: 'includeDeprecated',
                       type: {
-                        kind: 'SCALAR',
-                        name: 'Boolean',
-                        ofType: null,
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'SCALAR',
+                          name: 'Boolean',
+                          ofType: null,
+                        },
                       },
                       defaultValue: 'false',
                     },
@@ -309,9 +313,13 @@ describe('Introspection', () => {
                     {
                       name: 'includeDeprecated',
                       type: {
-                        kind: 'SCALAR',
-                        name: 'Boolean',
-                        ofType: null,
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'SCALAR',
+                          name: 'Boolean',
+                          ofType: null,
+                        },
                       },
                       defaultValue: 'false',
                     },
@@ -338,9 +346,13 @@ describe('Introspection', () => {
                     {
                       name: 'includeDeprecated',
                       type: {
-                        kind: 'SCALAR',
-                        name: 'Boolean',
-                        ofType: null,
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'SCALAR',
+                          name: 'Boolean',
+                          ofType: null,
+                        },
                       },
                       defaultValue: 'false',
                     },
@@ -477,9 +489,13 @@ describe('Introspection', () => {
                     {
                       name: 'includeDeprecated',
                       type: {
-                        kind: 'SCALAR',
-                        name: 'Boolean',
-                        ofType: null,
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'SCALAR',
+                          name: 'Boolean',
+                          ofType: null,
+                        },
                       },
                       defaultValue: 'false',
                     },
@@ -778,9 +794,13 @@ describe('Introspection', () => {
                     {
                       name: 'includeDeprecated',
                       type: {
-                        kind: 'SCALAR',
-                        name: 'Boolean',
-                        ofType: null,
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'SCALAR',
+                          name: 'Boolean',
+                          ofType: null,
+                        },
                       },
                       defaultValue: 'false',
                     },
diff --git a/src/type/introspection.ts b/src/type/introspection.ts
index fc214bed3d..e9181f53ca 100644
--- a/src/type/introspection.ts
+++ b/src/type/introspection.ts
@@ -107,7 +107,7 @@ export const __Directive: GraphQLObjectType = new GraphQLObjectType({
         ),
         args: {
           includeDeprecated: {
-            type: GraphQLBoolean,
+            type: new GraphQLNonNull(GraphQLBoolean),
             default: { value: false },
           },
         },
@@ -266,7 +266,7 @@ export const __Type: GraphQLObjectType = new GraphQLObjectType({
         type: new GraphQLList(new GraphQLNonNull(__Field)),
         args: {
           includeDeprecated: {
-            type: GraphQLBoolean,
+            type: new GraphQLNonNull(GraphQLBoolean),
             default: { value: false },
           },
         },
@@ -299,7 +299,7 @@ export const __Type: GraphQLObjectType = new GraphQLObjectType({
         type: new GraphQLList(new GraphQLNonNull(__EnumValue)),
         args: {
           includeDeprecated: {
-            type: GraphQLBoolean,
+            type: new GraphQLNonNull(GraphQLBoolean),
             default: { value: false },
           },
         },
@@ -316,7 +316,7 @@ export const __Type: GraphQLObjectType = new GraphQLObjectType({
         type: new GraphQLList(new GraphQLNonNull(__InputValue)),
         args: {
           includeDeprecated: {
-            type: GraphQLBoolean,
+            type: new GraphQLNonNull(GraphQLBoolean),
             default: { value: false },
           },
         },
@@ -364,7 +364,7 @@ export const __Field: GraphQLObjectType = new GraphQLObjectType({
         ),
         args: {
           includeDeprecated: {
-            type: GraphQLBoolean,
+            type: new GraphQLNonNull(GraphQLBoolean),
             default: { value: false },
           },
         },
diff --git a/src/utilities/__tests__/printSchema-test.ts b/src/utilities/__tests__/printSchema-test.ts
index 3c28907f40..b03e01026e 100644
--- a/src/utilities/__tests__/printSchema-test.ts
+++ b/src/utilities/__tests__/printSchema-test.ts
@@ -855,11 +855,11 @@ describe('Type System Printer', () => {
         name: String
         description: String
         specifiedByURL: String
-        fields(includeDeprecated: Boolean = false): [__Field!]
+        fields(includeDeprecated: Boolean! = false): [__Field!]
         interfaces: [__Type!]
         possibleTypes: [__Type!]
-        enumValues(includeDeprecated: Boolean = false): [__EnumValue!]
-        inputFields(includeDeprecated: Boolean = false): [__InputValue!]
+        enumValues(includeDeprecated: Boolean! = false): [__EnumValue!]
+        inputFields(includeDeprecated: Boolean! = false): [__InputValue!]
         ofType: __Type
         isOneOf: Boolean
       }
@@ -903,7 +903,7 @@ describe('Type System Printer', () => {
       type __Field {
         name: String!
         description: String
-        args(includeDeprecated: Boolean = false): [__InputValue!]!
+        args(includeDeprecated: Boolean! = false): [__InputValue!]!
         type: __Type!
         isDeprecated: Boolean!
         deprecationReason: String
@@ -945,7 +945,7 @@ describe('Type System Printer', () => {
         description: String
         isRepeatable: Boolean!
         locations: [__DirectiveLocation!]!
-        args(includeDeprecated: Boolean = false): [__InputValue!]!
+        args(includeDeprecated: Boolean! = false): [__InputValue!]!
       }
 
       """