diff --git a/__tests__/EnvironmentUpdater.spec.ts b/__tests__/EnvironmentUpdater.spec.ts
index 1d32beb..e0ed396 100644
--- a/__tests__/EnvironmentUpdater.spec.ts
+++ b/__tests__/EnvironmentUpdater.spec.ts
@@ -2,18 +2,25 @@ import * as rsconnect from '../src/main'
 
 describe('EnvironmentUpdater', () => {
   let eu: rsconnect.EnvironmentUpdater
+  let client: FakeAPIClient
 
   beforeEach(() => {
-    eu = new rsconnect.EnvironmentUpdater(new FakeAPIClient())
+    client = new FakeAPIClient()
+    eu = new rsconnect.EnvironmentUpdater(client)
     process.chdir = jest.fn()
   })
 
   describe('updateAppEnvironment', () => {
     it('works', async () => {
       process.env.CONNECT_ENV_SET_SECRET = 'eye of newt'
-      const env = await eu.updateAppEnvironment(42, './somewhar/up/er')
-      expect(env.get('MODE')).toBe('ludicrous')
-      expect(env.get('SECRET')).toBe('eye of newt')
+      const vars = await eu.updateAppEnvironment('the-content-guid', './somewhar/up/er')
+      expect(vars.sort((a, b) => a.localeCompare(b))).toStrictEqual(['MODE', 'SECRET'])
+      expect(client.fakeState).toStrictEqual({
+        'the-content-guid': {
+          MODE: 'ludicrous',
+          SECRET: 'eye of newt'
+        }
+      })
     })
   })
 })
@@ -27,31 +34,27 @@ class FakeAPIClient extends rsconnect.APIClient {
       apiKey: 'notAsEcRet'
     })
     this.fakeState = {
-      42: {
-        appId: 42,
-        version: 4,
-        values: {
-          MODE: 'ludicrous'
-        }
+      'the-content-guid': {
+        MODE: 'ludicrous'
       }
     }
   }
 
-  public async getAppEnvironment (appID: number): Promise<any> {
-    return this.fakeState[appID]
+  public async getAppEnvironment (appGUID: string): Promise<any> {
+    const state = this.fakeState[appGUID] !== undefined ? this.fakeState[appGUID] : {}
+    return Object.keys(state)
   }
 
-  public async updateAppEnvironment (appID: number, version: number, env: rsconnect.Environment): Promise<any> {
-    const origState = this.fakeState[appID] !== undefined ? this.fakeState[appID] : { values: {} }
-    this.fakeState[appID] = {
-      ...origState,
-      appId: appID,
-      version,
-      values: {
-        ...origState.values,
-        ...Object.fromEntries(env.entries())
+  public async updateAppEnvironment (appGUID: string, env: rsconnect.Environment): Promise<any> {
+    const state = this.fakeState[appGUID] !== undefined ? this.fakeState[appGUID] : {}
+    Array.from(env.keys()).forEach(key => {
+      const value = env.get(key)
+      if (value === null || value === undefined) {
+        state.delete(key)
+      } else {
+        state[key] = value
       }
-    }
-    return {}
+    })
+    this.fakeState[appGUID] = state
   }
 }
diff --git a/src/APIClient.ts b/src/APIClient.ts
index c649a52..4d3d02d 100644
--- a/src/APIClient.ts
+++ b/src/APIClient.ts
@@ -7,7 +7,6 @@ import qs from 'qs'
 import { debugLog, debugEnabled } from './debugLog'
 import {
   Application,
-  AppEnvironmentResponse,
   ClientTaskResponse,
   ExtendedBundleResponse,
   ListApplicationsParams,
@@ -139,19 +138,17 @@ export class APIClient {
       })
   }
 
-  public async getAppEnvironment (appID: number): Promise<AppEnvironmentResponse> {
-    return await this.client.get(`applications/${appID}/environment`)
-      .then((resp: AxiosResponse) => {
-        const camelized = keysToCamel(resp.data)
-        camelized.values = resp.data.values
-        return camelized
-      })
+  public async getAppEnvironment (appGUID: string): Promise<string[]> {
+    return await this.client.get(`v1/content/${appGUID}/environment`)
+      .then((resp: AxiosResponse) => resp.data)
   }
 
-  public async updateAppEnvironment (appID: number, version: number, env: Environment): Promise<AxiosResponse> {
-    return await this.client.post(
-      `applications/${appID}/environment`,
-      { app_id: appID, version, values: Object.fromEntries(env.entries()) }
+  public async updateAppEnvironment (appGUID: string, env: Environment): Promise<AxiosResponse> {
+    return await this.client.patch(
+      `v1/content/${appGUID}/environment`,
+      Array.from(env.keys()).map(key => {
+        return { name: key, value: env.get(key) }
+      })
     )
   }
 
diff --git a/src/EnvironmentUpdater.ts b/src/EnvironmentUpdater.ts
index 105deee..d057271 100644
--- a/src/EnvironmentUpdater.ts
+++ b/src/EnvironmentUpdater.ts
@@ -1,6 +1,5 @@
 import { APIClient } from './APIClient'
 import { Environment } from './Environment'
-import { AppEnvironmentResponse } from './api-types'
 import { debugLog } from './debugLog'
 
 export class EnvironmentUpdater {
@@ -10,14 +9,13 @@ export class EnvironmentUpdater {
     this.client = client
   }
 
-  public async updateAppEnvironment (appID: number, dir: string = '.'): Promise<Environment> {
+  public async updateAppEnvironment (appGUID: string, dir: string = '.'): Promise<string[]> {
     debugLog(() => [
-      'EnvironmentUpdater: updating environment for',
-      `app=${appID}`,
+      'EnvironmentUpdater: loading environment for',
+      `app=${appGUID}`,
       `dir=${dir}`
     ].join(' '))
 
-    const { version } = await this.client.getAppEnvironment(appID)
     const curDir = process.cwd()
     const env = new Environment()
 
@@ -31,33 +29,28 @@ export class EnvironmentUpdater {
     if (env.size === 0) {
       debugLog(() => [
         'EnvironmentUpdater: no environment variables found for',
-        `app=${appID}`,
+        `app=${appGUID}`,
+        `dir=${dir}`
+      ].join(' '))
+    } else {
+      debugLog(() => [
+        'EnvironmentUpdater: updating environment for',
+        `app=${appGUID}`,
         `dir=${dir}`
       ].join(' '))
-      return env
-    }
 
-    debugLog(() => [
-      'EnvironmentUpdater: updating environment based on',
-      `version=${version}`,
-      'for',
-      `app=${appID}`,
-      `dir=${dir}`
-    ].join(' '))
+      await this.client.updateAppEnvironment(appGUID, env)
+    }
 
-    await this.client.updateAppEnvironment(appID, version, env)
-    return await this.client.getAppEnvironment(appID)
-      .then((resp: AppEnvironmentResponse) => {
+    return await this.client.getAppEnvironment(appGUID)
+      .then((resp: string[]) => {
         debugLog(() => [
-          'EnvironmentUpdater: converting env object to map',
+          'EnvironmentUpdater: active environment variables for',
+          `app=${appGUID}`,
           `resp=${JSON.stringify(resp)}`
         ].join(' '))
 
-        const newEnv = new Environment()
-        for (const key in resp.values) {
-          newEnv.set(key, resp.values[key])
-        }
-        return newEnv
+        return resp
       })
   }
 }
diff --git a/src/api-types.ts b/src/api-types.ts
index a3e825f..2fb5d28 100644
--- a/src/api-types.ts
+++ b/src/api-types.ts
@@ -8,13 +8,6 @@ export interface AppGitRecord {
   lastError: string
 }
 
-export interface AppEnvironmentResponse {
-  appId: number
-  appGuid: string
-  version: number
-  values: any
-}
-
 export interface Application {
   id: number
   guid: string