diff --git a/src/objectKeys.ts b/src/objectKeys.ts
index 0370131..00f1df6 100644
--- a/src/objectKeys.ts
+++ b/src/objectKeys.ts
@@ -1,4 +1,4 @@
 /** https://docs.tsafe.dev/objectKeys */
-export function objectKeys<T extends Record<string, unknown>>(o: T): (keyof T)[] {
+export function objectKeys<T extends Record<string, unknown>>(o: T): (keyof T & string)[] {
     return Object.keys(o) as any;
 }
diff --git a/test/objectKeys.ts b/test/objectKeys.ts
index 067fa90..97c9205 100644
--- a/test/objectKeys.ts
+++ b/test/objectKeys.ts
@@ -39,3 +39,19 @@ import { same } from "evt/tools/inDepth/same";
 
     console.log("PASS TEST 2");
 }
+
+{
+    type A = {
+        [key: string]: boolean;
+    };
+
+    const a: A = { isNormalUser: false, isAdmin: true };
+
+    const got = objectKeys(a);
+
+    const expected = ["isNormalUser", "isAdmin"];
+
+    assert(same(got, expected));
+
+    console.log("PASS TEST 3");
+}