diff --git a/spec-dtslint/operators/scan-spec.ts b/spec-dtslint/operators/scan-spec.ts
new file mode 100644
index 0000000000..7f11324c9f
--- /dev/null
+++ b/spec-dtslint/operators/scan-spec.ts
@@ -0,0 +1,19 @@
+import { of } from 'rxjs';
+import { scan } from 'rxjs/operators';
+
+it('should enforce parameter', () => {
+  const a = of(1, 2, 3).pipe(scan()); // $ExpectError
+});
+
+it('should infer correctly ', () => {
+  const a = of(1, 2, 3).pipe(scan((x, y, z) => x + 1)); // $ExpectType Observable<number>
+});
+
+it('should infer correctly for accumulator of type array', () => {
+  const a = of(1, 2, 3).pipe(scan((x: number[], y: number, i: number) => x, [])); // $ExpectType Observable<number[]>
+});
+
+it('should accept seed parameter of the same type', () => {
+  const a = of(1, 2, 3).pipe(scan((x, y, z) => x + 1, 5)); // $ExpectType Observable<number>
+  const b = of(1, 2, 3).pipe(scan((x, y, z) => x + 1, '5')); // $ExpectError
+});