diff --git a/common/contract.ts b/common/contract.ts
index f7cd1407..f75cfa4b 100644
--- a/common/contract.ts
+++ b/common/contract.ts
@@ -92,6 +92,7 @@ export type Numeric = {
 
 export type outcomeType = AnyOutcomeType['outcomeType']
 export type resolution = 'YES' | 'NO' | 'MKT' | 'CANCEL'
+export const RESOLUTIONS = ['YES', 'NO', 'MKT', 'CANCEL'] as const
 export const OUTCOME_TYPES = ['BINARY', 'FREE_RESPONSE', 'NUMERIC'] as const
 export const MAX_QUESTION_LENGTH = 480
 export const MAX_DESCRIPTION_LENGTH = 10000
diff --git a/functions/src/resolve-market.ts b/functions/src/resolve-market.ts
index 183a5624..cf8c018f 100644
--- a/functions/src/resolve-market.ts
+++ b/functions/src/resolve-market.ts
@@ -2,7 +2,7 @@ import * as functions from 'firebase-functions'
 import * as admin from 'firebase-admin'
 import { difference, uniq, mapValues, groupBy, sumBy } from 'lodash'
 
-import { Contract } from '../../common/contract'
+import { Contract, resolution, RESOLUTIONS } from '../../common/contract'
 import { User } from '../../common/user'
 import { Bet } from '../../common/bet'
 import { getUser, isProd, payUser } from './utils'
@@ -21,7 +21,7 @@ export const resolveMarket = functions
   .https.onCall(
     async (
       data: {
-        outcome: string
+        outcome: resolution
         value?: number
         contractId: string
         probabilityInt?: number
@@ -42,7 +42,7 @@ export const resolveMarket = functions
       const { creatorId, outcomeType, closeTime } = contract
 
       if (outcomeType === 'BINARY') {
-        if (!['YES', 'NO', 'MKT', 'CANCEL'].includes(outcome))
+        if (!RESOLUTIONS.includes(outcome))
           return { status: 'error', message: 'Invalid outcome' }
       } else if (outcomeType === 'FREE_RESPONSE') {
         if (