diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
index 2917539cfd..c8e99f0d1d 100644
--- a/src/lib/es5.d.ts
+++ b/src/lib/es5.d.ts
@@ -1410,7 +1410,7 @@ type Readonly<T> = {
 };
 
 /**
- * From T pick a set of properties K
+ * From T, pick a set of properties whose keys are in the union K
  */
 type Pick<T, K extends keyof T> = {
     [P in K]: T[P];