diff --git a/src/vanilla/atom.ts b/src/vanilla/atom.ts
index b2cfcba268..045dad917e 100644
--- a/src/vanilla/atom.ts
+++ b/src/vanilla/atom.ts
@@ -75,6 +75,11 @@ export function atom<Value, Args extends unknown[], Result>(
 // read-only derived atom
 export function atom<Value>(read: Read<Value>): Atom<Value>
 
+// Value with default as initial value
+export function atom<Value = undefined>(
+  read: Read<Value | undefined>,
+): Atom<Value | undefined>
+
 // write-only derived atom
 export function atom<Value, Args extends unknown[], Result>(
   initialValue: Value,