diff --git a/types/estree/estree-tests.ts b/types/estree/estree-tests.ts
index 5cd065d03f..24e92ddc38 100644
--- a/types/estree/estree-tests.ts
+++ b/types/estree/estree-tests.ts
@@ -223,7 +223,8 @@ boolean = memberExpression.computed;
 
 // Declarations
 var functionDeclaration: ESTree.FunctionDeclaration;
-identifier = functionDeclaration.id;
+var identifierOrNull: ESTree.Identifier | null = functionDeclaration.id;
+functionDeclaration.id = null;
 var params: Array<ESTree.Pattern> = functionDeclaration.params;
 blockStatement = functionDeclaration.body;
 booleanMaybe = functionDeclaration.generator;
@@ -237,6 +238,10 @@ var variableDeclarator: ESTree.VariableDeclarator;
 pattern = variableDeclarator.id; // Pattern
 expressionMaybe = variableDeclarator.init;
 
+var classDeclaration: ESTree.ClassDeclaration;
+identifierOrNull = classDeclaration.id;
+classDeclaration.id = null;
+
 // Clauses
 // SwitchCase
 string = switchCase.type;
diff --git a/types/estree/index.d.ts b/types/estree/index.d.ts
index 068cbfd8ce..0133991c9f 100644
--- a/types/estree/index.d.ts
+++ b/types/estree/index.d.ts
@@ -196,7 +196,8 @@ interface BaseDeclaration extends BaseStatement { }
 
 export interface FunctionDeclaration extends BaseFunction, BaseDeclaration {
   type: "FunctionDeclaration";
-  id: Identifier;
+  /** It is null when a function declaration is a part of the `export default function` statement */
+  id: Identifier | null;
   body: BlockStatement;
 }
 
@@ -473,7 +474,8 @@ export interface MethodDefinition extends BaseNode {
 
 export interface ClassDeclaration extends BaseClass, BaseDeclaration {
   type: "ClassDeclaration";
-  id: Identifier;
+  /** It is null when a class declaration is a part of the `export default class` statement */
+  id: Identifier | null;
 }
 
 export interface ClassExpression extends BaseClass, BaseExpression {