diff --git a/flow-typed/npm/babel-types_v7.x.x.js b/flow-typed/npm/babel-types_v7.x.x.js
index 00aaa15964..c6b6cd7e64 100644
--- a/flow-typed/npm/babel-types_v7.x.x.js
+++ b/flow-typed/npm/babel-types_v7.x.x.js
@@ -3848,8 +3848,8 @@ declare module "@babel/types" {
   declare export function prependToMemberExpression(member: BabelNodeMemberExpression, prepend: BabelNodeExpression): BabelNodeMemberExpression
   declare export function removeProperties<T>(n: T, opts: ?{}): void;
   declare export function removePropertiesDeep<T>(n: T, opts: ?{}): T;
-  declare export function getBindingIdentifiers(node: BabelNode, duplicates: boolean, outerOnly?: boolean): { [key: string]: BabelNodeIdentifier | Array<BabelNodeIdentifier> }
-  declare export function getOuterBindingIdentifiers(node: Node, duplicates: boolean): { [key: string]: BabelNodeIdentifier | Array<BabelNodeIdentifier> }
+  declare export function getBindingIdentifiers(node: BabelNode, duplicates?: boolean, outerOnly?: boolean): { [key: string]: BabelNodeIdentifier | Array<BabelNodeIdentifier> }
+  declare export function getOuterBindingIdentifiers(node: Node, duplicates?: boolean): { [key: string]: BabelNodeIdentifier | Array<BabelNodeIdentifier> }
   declare export type TraversalAncestors = Array<{
     node: BabelNode,
     key: string,
diff --git a/scripts/support/generateBabelTypesFlowLibraryDefinition.js b/scripts/support/generateBabelTypesFlowLibraryDefinition.js
index 6bdab43ef8..48164b69ad 100644
--- a/scripts/support/generateBabelTypesFlowLibraryDefinition.js
+++ b/scripts/support/generateBabelTypesFlowLibraryDefinition.js
@@ -221,9 +221,9 @@ function main() {
 
     // retrievers/
     // eslint-disable-next-line max-len
-    `declare export function getBindingIdentifiers(node: ${NODE_PREFIX}, duplicates: boolean, outerOnly?: boolean): { [key: string]: ${NODE_PREFIX}Identifier | Array<${NODE_PREFIX}Identifier> }`,
+    `declare export function getBindingIdentifiers(node: ${NODE_PREFIX}, duplicates?: boolean, outerOnly?: boolean): { [key: string]: ${NODE_PREFIX}Identifier | Array<${NODE_PREFIX}Identifier> }`,
     // eslint-disable-next-line max-len
-    `declare export function getOuterBindingIdentifiers(node: Node, duplicates: boolean): { [key: string]: ${NODE_PREFIX}Identifier | Array<${NODE_PREFIX}Identifier> }`,
+    `declare export function getOuterBindingIdentifiers(node: Node, duplicates?: boolean): { [key: string]: ${NODE_PREFIX}Identifier | Array<${NODE_PREFIX}Identifier> }`,
 
     // traverse/
     `declare export type TraversalAncestors = Array<{