diff --git a/aio/content/examples/rx-library/src/operators.1.ts b/aio/content/examples/rx-library/src/operators.1.ts
index d9ea72920a..1949dfe47d 100644
--- a/aio/content/examples/rx-library/src/operators.1.ts
+++ b/aio/content/examples/rx-library/src/operators.1.ts
@@ -8,7 +8,7 @@ const nums = of(1, 2, 3, 4, 5);
 
 // Create a function that accepts an Observable.
 const squareOddVals = pipe(
-  filter(n => n % 2),
+  filter((n: number) => n % 2 !== 0),
   map(n => n * n)
 );