diff --git a/__tests__/base.js b/__tests__/base.js
index 8a856bc8..96c3e1a1 100644
--- a/__tests__/base.js
+++ b/__tests__/base.js
@@ -1,5 +1,5 @@
 "use strict"
-import produce, {setAutoFreeze, setUseProxies, nothing} from "../src/immer"
+import produce, {setAutoFreeze, setUseProxies, nothing, isDraft} from "../src/immer"
 import deepFreeze from "deep-freeze"
 import cloneDeep from "lodash.clonedeep"
 import * as lodash from "lodash"
@@ -1311,6 +1311,40 @@ function runBaseTest(name, useProxies, freeze, useListener) {
             return freeze ? deepFreeze(data) : data
         }
     })
+
+    describe(`isDraft - ${name}`, () => {
+        beforeAll(() => {
+            setAutoFreeze(freeze)
+            setUseProxies(useProxies)
+        })
+
+        it('returns true for object drafts', () => {
+            produce({}, state => {
+                expect(isDraft(state)).toBeTruthy()
+            })
+        })
+        it('returns true for array drafts', () => {
+            produce([], state => {
+                expect(isDraft(state)).toBeTruthy()
+            })
+        })
+        it('returns true for objects nested in object drafts', () => {
+            produce({ a: { b: {} } }, state => {
+                expect(isDraft(state.a)).toBeTruthy()
+                expect(isDraft(state.a.b)).toBeTruthy()
+            })
+        })
+        it('returns false for new objects added to a draft', () => {
+            produce({}, state => {
+                state.a = {}
+                expect(isDraft(state.a)).toBeFalsy()
+            })
+        })
+        it('returns false for a returned draft', () => {
+            const result = produce({}, state => state)
+            expect(isDraft(result)).toBeFalsy()
+        })
+    })
 }
 
 function enumerableOnly(x) {
diff --git a/src/immer.d.ts b/src/immer.d.ts
index 72495d78..9705c8e4 100644
--- a/src/immer.d.ts
+++ b/src/immer.d.ts
@@ -132,3 +132,5 @@ export function setUseProxies(useProxies: boolean): void
 export function applyPatches<S>(state: S, patches: Patch[]): S
 
 export function original<T>(value: T): T | void
+
+export function isDraft(value: any): boolean
diff --git a/src/immer.js b/src/immer.js
index fcbb4686..458476a1 100644
--- a/src/immer.js
+++ b/src/immer.js
@@ -1,4 +1,4 @@
-export {setAutoFreeze, setUseProxies, original} from "./common"
+export {setAutoFreeze, setUseProxies, original, isProxy as isDraft} from "./common"
 
 import {applyPatches as applyPatchesImpl} from "./patches"
 import {isProxyable, getUseProxies, NOTHING} from "./common"
diff --git a/src/immer.js.flow b/src/immer.js.flow
index 5702f2b3..73018431 100644
--- a/src/immer.js.flow
+++ b/src/immer.js.flow
@@ -87,4 +87,6 @@ declare export function setUseProxies(useProxies: boolean): void
 
 declare export function applyPatches<S>(state: S, patches: Patch[]): S
 
-declare export function original<S>(value: S): ?S
\ No newline at end of file
+declare export function original<S>(value: S): ?S
+
+declare export function isDraft(value: any): boolean