diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index fad42bcb8e..924c01885e 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -262,6 +262,8 @@ jobs:
             path: tests/events
           - cmd: cd tests/cashiers-check && anchor test
             path: tests/cashiers-check
+          - cmd: cd tests/declare-id && anchor test
+            path: tests/declare-id
           - cmd: cd tests/typescript && anchor test
             path: tests/typescript
           - cmd: cd tests/zero-copy && anchor test && cd programs/zero-copy && cargo test-bpf
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 023b1a7524..fd99ac2032 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,10 @@ incremented for features.
 
 ## [Unreleased]
 
+### Features
+
+* lang: add check that declared id == program id ([#1451](https://github.com/project-serum/anchor/pull/1451))
+
 ### Fixes
 
 * ts: Allow nullable types for `Option<T>` mapped types ([#1428](https://github.com/project-serum/anchor/pull/1428)).
diff --git a/lang/src/error.rs b/lang/src/error.rs
index 5e9a276cf0..73f444c974 100644
--- a/lang/src/error.rs
+++ b/lang/src/error.rs
@@ -154,6 +154,11 @@ pub enum ErrorCode {
     #[msg("The given state account does not have the correct address")]
     StateInvalidAddress = 4000,
 
+    // Miscellaneous
+    /// 4100 - The declared program id does not match actual program id
+    #[msg("The declared program id does not match the actual program id")]
+    DeclaredProgramIdMismatch = 4100,
+
     // Deprecated
     /// 5000 - The API being used is deprecated and should no longer be used
     #[msg("The API being used is deprecated and should no longer be used")]
diff --git a/lang/syn/src/codegen/program/entry.rs b/lang/syn/src/codegen/program/entry.rs
index 8f9bcb7bd9..af3dd360c5 100644
--- a/lang/syn/src/codegen/program/entry.rs
+++ b/lang/syn/src/codegen/program/entry.rs
@@ -56,6 +56,9 @@ pub fn generate(program: &Program) -> proc_macro2::TokenStream {
             {
                 msg!("anchor-debug is active");
             }
+            if *program_id != ID {
+                return Err(anchor_lang::error::ErrorCode::DeclaredProgramIdMismatch.into());
+            }
             if data.len() < 8 {
                 return #fallback_maybe
             }
diff --git a/tests/declare-id/Anchor.toml b/tests/declare-id/Anchor.toml
new file mode 100644
index 0000000000..0555c68f16
--- /dev/null
+++ b/tests/declare-id/Anchor.toml
@@ -0,0 +1,9 @@
+[provider]
+cluster = "localnet"
+wallet = "~/.config/solana/id.json"
+
+[programs.localnet]
+declare_id = "FJcF5c8HncdfAgjPjTH49GAEypkJCG2ZADh2xhduNi5B"
+
+[scripts]
+test = "yarn run mocha -t 1000000 tests/"
diff --git a/tests/declare-id/Cargo.toml b/tests/declare-id/Cargo.toml
new file mode 100644
index 0000000000..a60de986d3
--- /dev/null
+++ b/tests/declare-id/Cargo.toml
@@ -0,0 +1,4 @@
+[workspace]
+members = [
+    "programs/*"
+]
diff --git a/tests/declare-id/package.json b/tests/declare-id/package.json
new file mode 100644
index 0000000000..0be35fc5a2
--- /dev/null
+++ b/tests/declare-id/package.json
@@ -0,0 +1,19 @@
+{
+  "name": "declare-id",
+  "version": "0.21.0",
+  "license": "(MIT OR Apache-2.0)",
+  "homepage": "https://github.com/project-serum/anchor#readme",
+  "bugs": {
+    "url": "https://github.com/project-serum/anchor/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/project-serum/anchor.git"
+  },
+  "engines": {
+    "node": ">=11"
+  },
+  "scripts": {
+    "test": "anchor test"
+  }
+}
diff --git a/tests/declare-id/programs/declare-id/Cargo.toml b/tests/declare-id/programs/declare-id/Cargo.toml
new file mode 100644
index 0000000000..0bbbab6119
--- /dev/null
+++ b/tests/declare-id/programs/declare-id/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "declare-id"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "declare_id"
+
+[features]
+no-entrypoint = []
+cpi = ["no-entrypoint"]
+
+[dependencies]
+anchor-lang = { path = "../../../../lang" }
diff --git a/tests/declare-id/programs/declare-id/Xargo.toml b/tests/declare-id/programs/declare-id/Xargo.toml
new file mode 100644
index 0000000000..475fb71ed1
--- /dev/null
+++ b/tests/declare-id/programs/declare-id/Xargo.toml
@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []
diff --git a/tests/declare-id/programs/declare-id/src/lib.rs b/tests/declare-id/programs/declare-id/src/lib.rs
new file mode 100644
index 0000000000..5e98ce2e5c
--- /dev/null
+++ b/tests/declare-id/programs/declare-id/src/lib.rs
@@ -0,0 +1,18 @@
+use anchor_lang::prelude::*;
+
+// Intentionally different program id than the one defined in Anchor.toml.
+declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
+
+
+#[program]
+mod declare_id {
+    use super::*;
+
+    pub fn initialize(_ctx: Context<Initialize>) -> ProgramResult {
+        Ok(())
+    }
+}
+
+#[derive(Accounts)]
+pub struct Initialize {
+}
diff --git a/tests/declare-id/tests/declare-id.js b/tests/declare-id/tests/declare-id.js
new file mode 100644
index 0000000000..ca1c290a6a
--- /dev/null
+++ b/tests/declare-id/tests/declare-id.js
@@ -0,0 +1,17 @@
+const anchor = require("@project-serum/anchor");
+const splToken = require("@solana/spl-token");
+const assert = require("assert");
+
+describe("declare_id", () => {
+  anchor.setProvider(anchor.Provider.local());
+  const program = anchor.workspace.DeclareId;
+
+  it("throws error!", async () => {
+    try {
+      await program.rpc.initialize();
+      assert.ok(false);
+    } catch (err) {
+      assert.equal(err.code, 4100);
+    }
+  });
+});
diff --git a/tests/interface/programs/counter-auth/src/lib.rs b/tests/interface/programs/counter-auth/src/lib.rs
index a89af60ec1..2281bd3a3e 100644
--- a/tests/interface/programs/counter-auth/src/lib.rs
+++ b/tests/interface/programs/counter-auth/src/lib.rs
@@ -19,11 +19,11 @@ pub mod counter_auth {
         fn is_authorized(_ctx: Context<Empty>, current: u64, new: u64) -> ProgramResult {
             if current % 2 == 0 {
                 if new % 2 == 0 {
-                    return Err(ProgramError::Custom(50)); // Arbitrary error code.
+                    return Err(ProgramError::Custom(15000)); // Arbitrary error code.
                 }
             } else {
                 if new % 2 == 1 {
-                    return Err(ProgramError::Custom(60)); // Arbitrary error code.
+                    return Err(ProgramError::Custom(16000)); // Arbitrary error code.
                 }
             }
             Ok(())
diff --git a/tests/interface/tests/interface.js b/tests/interface/tests/interface.js
index 574cac9e51..c8997810be 100644
--- a/tests/interface/tests/interface.js
+++ b/tests/interface/tests/interface.js
@@ -25,7 +25,7 @@ describe("interface", () => {
         });
       },
       (err) => {
-        if (err.toString().split("custom program error: 0x32").length !== 2) {
+        if (err.toString().split("custom program error: 0x3a98").length !== 2) {
           return false;
         }
         return true;
@@ -33,7 +33,7 @@ describe("interface", () => {
     );
   });
 
-  it("Shold succeed to go from even to odd", async () => {
+  it("Should succeed to go from even to odd", async () => {
     await counter.state.rpc.setCount(new anchor.BN(3), {
       accounts: {
         authProgram: counterAuth.programId,
diff --git a/tests/package.json b/tests/package.json
index 40198cd2ed..7159a5d679 100644
--- a/tests/package.json
+++ b/tests/package.json
@@ -28,7 +28,8 @@
     "sysvars",
     "tictactoe",
     "typescript",
-    "zero-copy"
+    "zero-copy",
+    "declare-id"
   ],
   "dependencies": {
     "@project-serum/anchor": "^0.21.0",
diff --git a/tests/yarn.lock b/tests/yarn.lock
index 69ce24aeb5..14e85c6443 100644
--- a/tests/yarn.lock
+++ b/tests/yarn.lock
@@ -50,18 +50,19 @@
     snake-case "^3.0.4"
     toml "^3.0.0"
 
-"@project-serum/anchor@^0.20.0":
-  version "0.20.0"
-  resolved "https://registry.yarnpkg.com/@project-serum/anchor/-/anchor-0.20.0.tgz#547f5c0ff7e66809fa7118b2e3abd8087b5ec519"
-  integrity sha512-p1KOiqGBIbNsopMrSVoPwgxR1iPffsdjMNCOysahTPL9whX2CLX9HQCdopHjYaGl7+SdHRuXml6Wahk/wUmC8g==
+"@project-serum/anchor@^0.21.0":
+  version "0.21.0"
+  resolved "https://registry.yarnpkg.com/@project-serum/anchor/-/anchor-0.21.0.tgz#ad5fb33744991ec1900cdb2fd22707c908b12b5f"
+  integrity sha512-flRuW/F+iC8mitNokx82LOXyND7Dyk6n5UUPJpQv/+NfySFrNFlzuQZaBZJ4CG5g9s8HS/uaaIz1nVkDR8V/QA==
   dependencies:
-    "@project-serum/borsh" "^0.2.2"
+    "@project-serum/borsh" "^0.2.4"
     "@solana/web3.js" "^1.17.0"
     base64-js "^1.5.1"
     bn.js "^5.1.2"
     bs58 "^4.0.1"
     buffer-layout "^1.2.2"
     camelcase "^5.3.1"
+    cross-fetch "^3.1.5"
     crypto-hash "^1.3.0"
     eventemitter3 "^4.0.7"
     find "^0.3.0"
@@ -78,6 +79,14 @@
     bn.js "^5.1.2"
     buffer-layout "^1.2.0"
 
+"@project-serum/borsh@^0.2.4":
+  version "0.2.5"
+  resolved "https://registry.yarnpkg.com/@project-serum/borsh/-/borsh-0.2.5.tgz#6059287aa624ecebbfc0edd35e4c28ff987d8663"
+  integrity sha512-UmeUkUoKdQ7rhx6Leve1SssMR/Ghv8qrEiyywyxSWg7ooV7StdpPBhciiy5eB3T0qU1BXvdRNC8TdrkxK7WC5Q==
+  dependencies:
+    bn.js "^5.1.2"
+    buffer-layout "^1.2.0"
+
 "@project-serum/common@^0.0.1-beta.3":
   version "0.0.1-beta.3"
   resolved "https://registry.yarnpkg.com/@project-serum/common/-/common-0.0.1-beta.3.tgz#53586eaff9d9fd7e8938b1e12080c935b8b6ad07"
@@ -455,6 +464,13 @@ cross-fetch@^3.1.4:
   dependencies:
     node-fetch "2.6.1"
 
+cross-fetch@^3.1.5:
+  version "3.1.5"
+  resolved "https://registry.yarnpkg.com/cross-fetch/-/cross-fetch-3.1.5.tgz#e1389f44d9e7ba767907f7af8454787952ab534f"
+  integrity sha512-lvb1SBsI0Z7GDwmuid+mU3kWVBwTVUbe7S0H52yaaAdQOXq2YktTCZdlAcNKFzE6QtRz0snpw9bNiPeOIkkQvw==
+  dependencies:
+    node-fetch "2.6.7"
+
 crypto-hash@^1.3.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/crypto-hash/-/crypto-hash-1.3.0.tgz#b402cb08f4529e9f4f09346c3e275942f845e247"
@@ -906,6 +922,13 @@ node-fetch@2.6.1:
   resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.1.tgz#045bd323631f76ed2e2b55573394416b639a0052"
   integrity sha512-V4aYg89jEoVRxRb2fJdAg8FHvI7cEyYdVAh94HH0UIK8oJxUfkjlDQN9RbMx+bEjP7+ggMiFRprSti032Oipxw==
 
+node-fetch@2.6.7:
+  version "2.6.7"
+  resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.7.tgz#24de9fba827e3b4ae44dc8b20256a379160052ad"
+  integrity sha512-ZjMPFEfVx5j+y2yF35Kzx5sF7kDzxuDj6ziH4FFbOp87zKDZNx8yExJIb05OGF4Nlt9IHFIMBkRl41VdvcNdbQ==
+  dependencies:
+    whatwg-url "^5.0.0"
+
 node-gyp-build@^4.2.0, node-gyp-build@^4.3.0:
   version "4.3.0"
   resolved "https://registry.yarnpkg.com/node-gyp-build/-/node-gyp-build-4.3.0.tgz#9f256b03e5826150be39c764bf51e993946d71a3"
@@ -1127,6 +1150,11 @@ toml@^3.0.0:
   resolved "https://registry.yarnpkg.com/toml/-/toml-3.0.0.tgz#342160f1af1904ec9d204d03a5d61222d762c5ee"
   integrity sha512-y/mWCZinnvxjTKYhJ+pYxwD0mRLVvOtdS2Awbgxln6iEnt4rk0yBxeSBHkGJcPucRiG0e55mwWp+g/05rsrd6w==
 
+tr46@~0.0.3:
+  version "0.0.3"
+  resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"
+  integrity sha1-gYT9NH2snNwYWZLzpmIuFLnZq2o=
+
 traverse-chain@~0.1.0:
   version "0.1.0"
   resolved "https://registry.yarnpkg.com/traverse-chain/-/traverse-chain-0.1.0.tgz#61dbc2d53b69ff6091a12a168fd7d433107e40f1"
@@ -1202,6 +1230,19 @@ uuid@^8.3.0:
   resolved "https://registry.yarnpkg.com/uuid/-/uuid-8.3.2.tgz#80d5b5ced271bb9af6c445f21a1a04c606cefbe2"
   integrity sha512-+NYs2QeMWy+GWFOEm9xnn6HCDp0l7QBD7ml8zLUmJ+93Q5NF0NocErnwkTkXVFNiX3/fpC6afS8Dhb/gz7R7eg==
 
+webidl-conversions@^3.0.0:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/webidl-conversions/-/webidl-conversions-3.0.1.tgz#24534275e2a7bc6be7bc86611cc16ae0a5654871"
+  integrity sha1-JFNCdeKnvGvnvIZhHMFq4KVlSHE=
+
+whatwg-url@^5.0.0:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/whatwg-url/-/whatwg-url-5.0.0.tgz#966454e8765462e37644d3626f6742ce8b70965d"
+  integrity sha1-lmRU6HZUYuN2RNNib2dCzotwll0=
+  dependencies:
+    tr46 "~0.0.3"
+    webidl-conversions "^3.0.0"
+
 which@2.0.2:
   version "2.0.2"
   resolved "https://registry.yarnpkg.com/which/-/which-2.0.2.tgz#7c6a8dd0a636a0327e10b59c9286eee93f3f51b1"
diff --git a/ts/src/error.ts b/ts/src/error.ts
index 52dffd7798..e9bdbc5f27 100644
--- a/ts/src/error.ts
+++ b/ts/src/error.ts
@@ -102,6 +102,9 @@ const LangErrorCode = {
   // State.
   StateInvalidAddress: 4000,
 
+  // Miscellaneous
+  DeclaredProgramIdMismatch: 4100,
+
   // Used for APIs that shouldn't be used anymore.
   Deprecated: 5000,
 };
@@ -219,7 +222,13 @@ const LangErrorMessage = new Map([
     "The given state account does not have the correct address",
   ],
 
-  // Misc.
+  // Miscellaneous
+  [
+    LangErrorCode.DeclaredProgramIdMismatch,
+    "The declared program id does not match the actual program id",
+  ],
+
+  // Deprecated
   [
     LangErrorCode.Deprecated,
     "The API being used is deprecated and should no longer be used",