diff --git a/book-content/chapters/16-the-utils-folder.md b/book-content/chapters/16-the-utils-folder.md
index 3694077..d4bb8b6 100644
--- a/book-content/chapters/16-the-utils-folder.md
+++ b/book-content/chapters/16-the-utils-folder.md
@@ -496,8 +496,9 @@ function assertIsAlbum(input: unknown): asserts input is Album {
     "artist" in input &&
     "year" in input
   ) {
-    throw new Error("Not an Album!");
+    return;
   }
+  throw new Error("Not an Album!");
 }
 ```
 
@@ -522,8 +523,9 @@ function assertIsAlbum(input: unknown): asserts input is Album {
     "artist" in input &&
     "year" in input
   ) {
-    throw new Error("Not an Album!");
+    return;
   }
+  throw new Error("Not an Album!");
 }
 // ---cut---
 function getAlbumTitle(item: unknown) {
@@ -548,11 +550,12 @@ For example, if the `assertIsAlbum` function doesn't check for all the required
 ```typescript
 function assertIsAlbum(input: unknown): asserts input is Album {
   if (typeof input === "object") {
-    throw new Error("Not an Album!");
+    return;
   }
+  throw new Error("Not an Album!");
 }
 
-let item = null;
+let item: unknown = null;
 
 assertIsAlbum(item);
 
@@ -877,7 +880,7 @@ it("Should accept a custom error", () => {
 
 Your task is to update the `addCodeToError` type signature to enforce the required constraints so that `TError` is required to have a `message` property and can optionally have a `code` property.
 
-<Exercise title="Exercise 4: Type Parameter Constraints" filePath="/src/085-the-utils-folder/216-type-parameter-defaults-in-generic-functions.problem.ts"></Exercise>
+<Exercise title="Exercise 4: Type Parameter Constraints" filePath="/src/085-the-utils-folder/218-type-parameter-constraints-with-generic-functions.problem"></Exercise>
 
 ### Exercise 5: Combining Generic Types and Functions