diff --git a/web/src/app/rotations/util.test.ts b/web/src/app/rotations/util.test.ts
index daed35693f..2d7a5fbf67 100644
--- a/web/src/app/rotations/util.test.ts
+++ b/web/src/app/rotations/util.test.ts
@@ -1,6 +1,10 @@
-import { calcNewActiveIndex, handoffSummary, reorderList } from './util'
+import {
+  calcNewActiveIndex,
+  handoffSummary,
+  HandoffSummaryInput,
+  reorderList,
+} from './util'
 import { Settings, Zone } from 'luxon'
-import { CreateRotationInput } from '../../schema'
 
 let oldZone: Zone
 beforeAll(() => {
@@ -45,7 +49,7 @@ describe('calcNewActiveIndex', () => {
 })
 
 describe('handoffSummary', () => {
-  const check = (rotation: Partial<CreateRotationInput>, exp: string): void => {
+  const check = (rotation: HandoffSummaryInput, exp: string): void => {
     expect(handoffSummary(rotation)).toBe(exp)
   }
 
diff --git a/web/src/app/rotations/util.js b/web/src/app/rotations/util.tsx
similarity index 81%
rename from web/src/app/rotations/util.js
rename to web/src/app/rotations/util.tsx
index e90460c271..ffd914dc05 100644
--- a/web/src/app/rotations/util.js
+++ b/web/src/app/rotations/util.tsx
@@ -1,8 +1,13 @@
 import { DateTime } from 'luxon'
+import { CreateRotationInput, RotationType } from '../../schema'
 
 // calcNewActiveIndex returns the newActiveIndex for a swap operation
 // -1 will be returned if there was no change
-export function calcNewActiveIndex(oldActiveIndex, oldIndex, newIndex) {
+export function calcNewActiveIndex(
+  oldActiveIndex: number,
+  oldIndex: number,
+  newIndex: number,
+): number {
   if (oldIndex === newIndex) {
     return -1
   }
@@ -21,7 +26,7 @@ export function calcNewActiveIndex(oldActiveIndex, oldIndex, newIndex) {
 }
 
 // formatTime returns the formatted time with the timezone (if different than local timezone)
-export function formatTime(time, tz) {
+export function formatTime(time: string, tz: string): string {
   const schedTime = DateTime.fromISO(time, { zone: tz }).toLocaleString(
     DateTime.TIME_SIMPLE,
   )
@@ -36,7 +41,7 @@ export function formatTime(time, tz) {
 }
 
 // formatDay returns the day given a time and timezone
-export function formatDay(time, tz) {
+export function formatDay(time: string, tz: string): string {
   const day = DateTime.fromISO(time, { zone: tz }).weekdayLong
   const localDay = DateTime.fromISO(time).weekdayLong
 
@@ -49,7 +54,11 @@ export function formatDay(time, tz) {
 
 // formatWeeklySummary returns the summary for a weekly rotation
 // taking into consideration extra formatting needed if timezone does not match with local timezone
-export function formatWeeklySummary(shiftLength, start, tz) {
+export function formatWeeklySummary(
+  shiftLength: number,
+  start: string,
+  tz: string,
+): string {
   let details = ''
   const day = DateTime.fromISO(start, { zone: tz }).weekdayLong
   const schedTime = DateTime.fromISO(start, { zone: tz }).toLocaleString(
@@ -71,8 +80,14 @@ export function formatWeeklySummary(shiftLength, start, tz) {
   return details
 }
 
+export interface HandoffSummaryInput extends Partial<CreateRotationInput> {
+  start: string
+  shiftLength: number
+  type: RotationType
+}
+
 // handoffSummary returns the summary description for the rotation
-export function handoffSummary(rotation) {
+export function handoffSummary(rotation: HandoffSummaryInput): string {
   const tz = rotation.timeZone
 
   if (!tz) return 'Loading handoff information...'
@@ -106,7 +121,11 @@ export function handoffSummary(rotation) {
 
 // reorderList will move an item from the oldIndex to the newIndex, preserving order
 // returning the result as a new array.
-export function reorderList(_items, oldIndex, newIndex) {
+export function reorderList(
+  _items: unknown[],
+  oldIndex: number,
+  newIndex: number,
+): unknown[] {
   const items = _items.slice()
   items.splice(oldIndex, 1) // remove 1 element from oldIndex position
   items.splice(newIndex, 0, _items[oldIndex]) // add dest to newIndex position