diff --git a/.changeset/rich-eggs-tease.md b/.changeset/rich-eggs-tease.md
new file mode 100644
index 000000000000..426fdc325635
--- /dev/null
+++ b/.changeset/rich-eggs-tease.md
@@ -0,0 +1,10 @@
+---
+'@solana/errors': patch
+'@solana/rpc': patch
+'@solana/rpc-subscriptions': patch
+'@solana/rpc-subscriptions-transport-websocket': patch
+'@solana/rpc-transport-http': patch
+'@solana/webcrypto-ed25519-polyfill': patch
+---
+
+`__DEV__` mode will now be the default if you don't set `process.env.NODE_ENV` at all. This means fewer people ‘accidentally’ finding themselves in production mode with minified error messages.
diff --git a/packages/build-scripts/dev-flag.ts b/packages/build-scripts/dev-flag.ts
index 3bdb1f27101d..f0b4fe044410 100644
--- a/packages/build-scripts/dev-flag.ts
+++ b/packages/build-scripts/dev-flag.ts
@@ -15,12 +15,12 @@ function replaceDev(source: string): string {
     const root = j(source);
     root.find(j.Identifier, { name: '__DEV__' }).replaceWith(() =>
         j.binaryExpression(
-            '===',
+            '!==',
             j.memberExpression(
                 j.memberExpression(j.identifier('process'), j.identifier('env')),
                 j.identifier('NODE_ENV'),
             ),
-            j.stringLiteral('development'),
+            j.stringLiteral('production'),
         ),
     );
     return root.toSource();
diff --git a/packages/rpc-subscriptions-spec/src/__tests__/rpc-subscription-test.ts b/packages/rpc-subscriptions-spec/src/__tests__/rpc-subscription-test.ts
index 9f0a3bd7e756..18857731135e 100644
--- a/packages/rpc-subscriptions-spec/src/__tests__/rpc-subscription-test.ts
+++ b/packages/rpc-subscriptions-spec/src/__tests__/rpc-subscription-test.ts
@@ -2,7 +2,6 @@ import {
     SOLANA_ERROR__RPC_SUBSCRIPTIONS__CANNOT_CREATE_SUBSCRIPTION_REQUEST,
     SOLANA_ERROR__RPC_SUBSCRIPTIONS__EXPECTED_SERVER_SUBSCRIPTION_ID,
     SolanaError,
-    SolanaErrorCode,
 } from '@solana/errors';
 import { createRpcMessage } from '@solana/rpc-spec-types';
 
@@ -263,12 +262,14 @@ describe('JSON-RPC 2.0 Subscriptions', () => {
         expect.assertions(1);
         iterable.mockImplementation(async function* () {
             yield Promise.resolve({
-                error: { code: 123, message: 'o no' },
+                error: { code: SOLANA_ERROR__RPC_SUBSCRIPTIONS__EXPECTED_SERVER_SUBSCRIPTION_ID },
                 id: 0,
             });
         });
         const subscribePromise = rpc.thingNotifications().subscribe({ abortSignal: new AbortController().signal });
-        await expect(subscribePromise).rejects.toThrow(new SolanaError(123 as SolanaErrorCode, undefined));
+        await expect(subscribePromise).rejects.toThrow(
+            new SolanaError(SOLANA_ERROR__RPC_SUBSCRIPTIONS__EXPECTED_SERVER_SUBSCRIPTION_ID),
+        );
     });
     it('throws errors when the connection fails to construct', async () => {
         expect.assertions(1);