diff --git a/src/__tests__/__snapshots__/exports.ts.snap b/src/__tests__/__snapshots__/exports.ts.snap
index 862d137bc13..82a7e0a1010 100644
--- a/src/__tests__/__snapshots__/exports.ts.snap
+++ b/src/__tests__/__snapshots__/exports.ts.snap
@@ -9,7 +9,6 @@ Array [
   "ApolloLink",
   "ApolloProvider",
   "Cache",
-  "DEV",
   "DocumentType",
   "HttpLink",
   "InMemoryCache",
@@ -65,7 +64,6 @@ exports[`exports of public entry points @apollo/client/cache 1`] = `
 Array [
   "ApolloCache",
   "Cache",
-  "DEV",
   "EntityStore",
   "InMemoryCache",
   "MissingFieldError",
@@ -87,7 +85,6 @@ Array [
   "ApolloError",
   "ApolloLink",
   "Cache",
-  "DEV",
   "HttpLink",
   "InMemoryCache",
   "MissingFieldError",
@@ -228,7 +225,6 @@ exports[`exports of public entry points @apollo/client/react 1`] = `
 Array [
   "ApolloConsumer",
   "ApolloProvider",
-  "DEV",
   "DocumentType",
   "getApolloContext",
   "operationName",
diff --git a/src/cache/index.ts b/src/cache/index.ts
index 53d5c650ae4..0aa33bdd2c8 100644
--- a/src/cache/index.ts
+++ b/src/cache/index.ts
@@ -1,4 +1,6 @@
-export { DEV } from "../utilities";
+import { invariant } from "ts-invariant";
+import { DEV } from "../utilities";
+invariant("boolean" === typeof DEV, DEV);
 
 export { Transaction, ApolloCache } from './core/cache';
 export { Cache } from './core/types/Cache';
diff --git a/src/core/index.ts b/src/core/index.ts
index 14e5084b701..b3723e5af78 100644
--- a/src/core/index.ts
+++ b/src/core/index.ts
@@ -1,6 +1,6 @@
 /* Core */
 
-export { DEV } from "../utilities";
+import { DEV } from "../utilities";
 
 export {
   ApolloClient,
@@ -91,7 +91,7 @@ export {
 // Note that all invariant.* logging is hidden in production.
 import { setVerbosity } from "ts-invariant";
 export { setVerbosity as setLogVerbosity }
-setVerbosity("log");
+setVerbosity(DEV ? "log" : "silent");
 
 // Note that importing `gql` by itself, then destructuring
 // additional properties separately before exporting, is intentional.
diff --git a/src/errors/index.ts b/src/errors/index.ts
index 956fa3df4e5..e053540cbed 100644
--- a/src/errors/index.ts
+++ b/src/errors/index.ts
@@ -1,3 +1,7 @@
+import { invariant } from "ts-invariant";
+import { DEV } from "../utilities";
+invariant("boolean" === typeof DEV, DEV);
+
 import { GraphQLError } from 'graphql';
 
 import { isNonEmptyArray } from '../utilities';
diff --git a/src/link/core/index.ts b/src/link/core/index.ts
index 8093e7c6cd2..b01ccf98897 100644
--- a/src/link/core/index.ts
+++ b/src/link/core/index.ts
@@ -1,3 +1,7 @@
+import { invariant } from "ts-invariant";
+import { DEV } from "../../utilities";
+invariant("boolean" === typeof DEV, DEV);
+
 export { empty } from './empty';
 export { from } from './from';
 export { split } from './split';
diff --git a/src/react/index.ts b/src/react/index.ts
index b3e508d44c5..eeee3f721a2 100644
--- a/src/react/index.ts
+++ b/src/react/index.ts
@@ -1,4 +1,6 @@
-export { DEV } from "../utilities";
+import { invariant } from "ts-invariant";
+import { DEV } from "../utilities";
+invariant("boolean" === typeof DEV, DEV);
 
 export {
   ApolloProvider,
diff --git a/src/testing/index.ts b/src/testing/index.ts
index bec83b671fe..831c6de2b10 100644
--- a/src/testing/index.ts
+++ b/src/testing/index.ts
@@ -1 +1,4 @@
+import { invariant } from "ts-invariant";
+import { DEV } from "../utilities";
+invariant("boolean" === typeof DEV, DEV);
 export * from '../utilities/testing';
diff --git a/src/utilities/index.ts b/src/utilities/index.ts
index 40c7bdde254..5ad7f9f5581 100644
--- a/src/utilities/index.ts
+++ b/src/utilities/index.ts
@@ -1,4 +1,6 @@
+import { invariant } from "ts-invariant";
 import { DEV } from "./globals";
+invariant("boolean" === typeof DEV, DEV);
 export { DEV }
 
 export {