diff --git a/packages/storage/src/__tests__/index.test.ts b/packages/storage/src/__tests__/index.test.ts
index 200de6aa2..1ba64e3cd 100644
--- a/packages/storage/src/__tests__/index.test.ts
+++ b/packages/storage/src/__tests__/index.test.ts
@@ -1315,6 +1315,18 @@ describe('Storage Utils', () => {
         });
         expectTypeOf(item).toEqualTypeOf<WxtStorageItem<number | null, {}>>();
       });
+
+      it('should define a non-null value when options are passed with a non-null init function', () => {
+        const item = storage.defineItem(`local:test`, {
+          init: () => 123,
+        });
+        expectTypeOf(item).toEqualTypeOf<WxtStorageItem<number, {}>>();
+
+        const item2 = storage.defineItem(`local:test`, {
+          init: () => Promise.resolve(123),
+        });
+        expectTypeOf(item2).toEqualTypeOf<WxtStorageItem<number, {}>>();
+      });
     });
   });
 
diff --git a/packages/storage/src/index.ts b/packages/storage/src/index.ts
index 76e438251..790d4337f 100644
--- a/packages/storage/src/index.ts
+++ b/packages/storage/src/index.ts
@@ -749,6 +749,12 @@ export interface WxtStorage {
     key: StorageItemKey,
     options: WxtStorageItemOptions<TValue> & { defaultValue: TValue },
   ): WxtStorageItem<TValue, TMetadata>;
+  defineItem<TValue, TMetadata extends Record<string, unknown> = {}>(
+    key: StorageItemKey,
+    options: WxtStorageItemOptions<TValue> & {
+      init: () => TValue | Promise<TValue>;
+    },
+  ): WxtStorageItem<TValue, TMetadata>;
   defineItem<TValue, TMetadata extends Record<string, unknown> = {}>(
     key: StorageItemKey,
     options: WxtStorageItemOptions<TValue>,