diff --git a/src/language/lexer.d.ts b/src/language/lexer.d.ts
index 92484b6ccd..40dbf9a6b2 100644
--- a/src/language/lexer.d.ts
+++ b/src/language/lexer.d.ts
@@ -1,5 +1,6 @@
 import { Token } from './ast';
 import { Source } from './source';
+import { TokenKindEnum } from './tokenKind';
 
 /**
  * Given a Source object, this returns a Lexer for that source.
@@ -50,3 +51,8 @@ export class Lexer {
  * @internal
  */
 export function isPunctuatorToken(token: Token): boolean;
+
+/**
+ * @internal
+ */
+export function isPunctuatorTokenKind(kind: TokenKindEnum): boolean;
diff --git a/src/type/definition.d.ts b/src/type/definition.d.ts
index 2c1d55f723..7036861aab 100644
--- a/src/type/definition.d.ts
+++ b/src/type/definition.d.ts
@@ -335,7 +335,7 @@ export interface GraphQLScalarTypeConfig<TInternal, TExternal> {
   description?: Maybe<string>;
   specifiedByUrl?: Maybe<string>;
   // Serializes an internal value to include in a response.
-  serialize: GraphQLScalarSerializer<TExternal>;
+  serialize?: GraphQLScalarSerializer<TExternal>;
   // Parses an externally provided value to use as an input.
   parseValue?: GraphQLScalarValueParser<TInternal>;
   // Parses an externally provided literal value to use as an input.
diff --git a/src/type/schema.d.ts b/src/type/schema.d.ts
index ab71fdc0b3..1ae844362a 100644
--- a/src/type/schema.d.ts
+++ b/src/type/schema.d.ts
@@ -111,7 +111,7 @@ export interface GraphQLSchemaValidationOptions {
 
 export interface GraphQLSchemaConfig extends GraphQLSchemaValidationOptions {
   description?: Maybe<string>;
-  query: Maybe<GraphQLObjectType>;
+  query?: Maybe<GraphQLObjectType>;
   mutation?: Maybe<GraphQLObjectType>;
   subscription?: Maybe<GraphQLObjectType>;
   types?: Maybe<Array<GraphQLNamedType>>;
diff --git a/src/utilities/getIntrospectionQuery.d.ts b/src/utilities/getIntrospectionQuery.d.ts
index 48ca92a4bf..b1822168ec 100644
--- a/src/utilities/getIntrospectionQuery.d.ts
+++ b/src/utilities/getIntrospectionQuery.d.ts
@@ -5,7 +5,7 @@ import { DirectiveLocationEnum } from '../language/directiveLocation';
 export interface IntrospectionOptions {
   // Whether to include descriptions in the introspection result.
   // Default: true
-  descriptions: boolean;
+  descriptions?: boolean;
 
   // Whether to include `specifiedByUrl` in the introspection result.
   // Default: false
diff --git a/src/validation/rules/KnownTypeNamesRule.d.ts b/src/validation/rules/KnownTypeNamesRule.d.ts
index 6c4560e787..b7cd75d4a1 100644
--- a/src/validation/rules/KnownTypeNamesRule.d.ts
+++ b/src/validation/rules/KnownTypeNamesRule.d.ts
@@ -1,5 +1,5 @@
 import { ASTVisitor } from '../../language/visitor';
-import { ValidationContext } from '../ValidationContext';
+import { ValidationContext, SDLValidationContext } from '../ValidationContext';
 
 /**
  * Known type names
@@ -7,4 +7,6 @@ import { ValidationContext } from '../ValidationContext';
  * A GraphQL document is only valid if referenced types (specifically
  * variable definitions and fragment conditions) are defined by the type schema.
  */
-export function KnownTypeNamesRule(context: ValidationContext): ASTVisitor;
+export function KnownTypeNamesRule(
+  context: ValidationContext | SDLValidationContext,
+): ASTVisitor;