diff --git a/package.json b/package.json
index 45ccca43a..d3f6ed262 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     ],
     "scripts": {
         "build": "hardhat compile",
-        "build:ts": "yarn rimraf dist && tsc",
+        "build:ts": "yarn rimraf dist && tsc -p tsconfig.prod.json",
         "test": "hardhat test",
         "coverage": "hardhat coverage",
         "benchmark": "yarn test benchmark/*.ts",
diff --git a/test/migration/subTests.spec.ts b/test/migration/subTests.spec.ts
index 6fd75c9c0..5b0259654 100644
--- a/test/migration/subTests.spec.ts
+++ b/test/migration/subTests.spec.ts
@@ -1,5 +1,5 @@
 import { BigNumber } from "ethers";
-import { Contract } from "@ethersproject/contracts";
+import { Contract } from "ethers";
 import { parseEther } from "@ethersproject/units";
 import { expect } from "chai";
 import hre, { ethers, waffle } from "hardhat";
diff --git a/tsconfig.json b/tsconfig.json
index 9e27a0645..bcb8d7515 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,23 +1,23 @@
 {
     "compilerOptions": {
-      "target": "es2017" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */,
-      "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */,
-      "lib": ["ES2015"],
-      "allowJs": false /* Allow javascript files to be compiled. */,
-      "declaration": true /* Generates corresponding '.d.ts' file. */,
-      "sourceMap": false /* Generates corresponding '.map' file. */,
-      "outDir": "./dist" /* Redirect output structure to the directory. */,
-      "strict": true /* Enable all strict type-checking options. */,
-      "noUnusedParameters": true /* Report errors on unused parameters. */,
-      "noImplicitReturns": true /* Report error when not all code paths in function return a value. */,
-      "noFallthroughCasesInSwitch": true /* Report errors for fallthrough cases in switch statement. */,
-      "moduleResolution": "node" /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */,
-      "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
-      "experimentalDecorators": true /* Enables experimental support for ES7 decorators. */,
-      "forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */,
-      "resolveJsonModule": true
+        "target": "es2017" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */,
+        "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */,
+        "lib": ["ES2015"],
+        "allowJs": false /* Allow javascript files to be compiled. */,
+        "declaration": true /* Generates corresponding '.d.ts' file. */,
+        "sourceMap": false /* Generates corresponding '.map' file. */,
+        "outDir": "./dist" /* Redirect output structure to the directory. */,
+        "strict": true /* Enable all strict type-checking options. */,
+        "noUnusedParameters": true /* Report errors on unused parameters. */,
+        "noImplicitReturns": true /* Report error when not all code paths in function return a value. */,
+        "noFallthroughCasesInSwitch": true /* Report errors for fallthrough cases in switch statement. */,
+        "moduleResolution": "node" /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */,
+        "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
+        "experimentalDecorators": true /* Enables experimental support for ES7 decorators. */,
+        "forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */,
+        "resolveJsonModule": true
     },
     "exclude": ["dist", "node_modules"],
-    "include": ["./src/index.ts", "./types"],
+    "include": ["./src/index.ts", "./types", "./test/**/*"],
     "files": ["./hardhat.config.ts"]
-  }
\ No newline at end of file
+}
diff --git a/tsconfig.prod.json b/tsconfig.prod.json
new file mode 100644
index 000000000..2e3140993
--- /dev/null
+++ b/tsconfig.prod.json
@@ -0,0 +1,4 @@
+{
+    "extends": "./tsconfig",
+    "exclude": ["./test/**/*"]
+}
diff --git a/yarn.lock b/yarn.lock
index ccb33ce94..51f8e29d4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7804,12 +7804,7 @@ prettier@^1.14.3:
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.19.1.tgz#f7d7f5ff8a9cd872a7be4ca142095956a60797cb"
   integrity sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==
 
-prettier@^2.1.2:
-  version "2.8.1"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-2.8.1.tgz#4e1fd11c34e2421bc1da9aea9bd8127cd0a35efc"
-  integrity sha512-lqGoSJBQNJidqCHE80vqZJHWHRFoNYsSpP9AjFhlhi9ODCJA541svILes/+/1GM3VaL/abZi7cpFzOpdR9UPKg==
-
-prettier@^2.8.4:
+prettier@^2.1.2, prettier@^2.8.4:
   version "2.8.4"
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-2.8.4.tgz#34dd2595629bfbb79d344ac4a91ff948694463c3"
   integrity sha512-vIS4Rlc2FNh0BySk3Wkd6xmwxB0FpOndW5fisM5H8hsZSxU2VWVB5CWIkIjWvrHjIhxk2g3bfMKM87zNTrZddw==
@@ -9524,20 +9519,13 @@ underscore@1.9.1:
   resolved "https://registry.yarnpkg.com/underscore/-/underscore-1.9.1.tgz#06dce34a0e68a7babc29b365b8e74b8925203961"
   integrity sha512-5/4etnCkd9c8gwgowi5/om/mYO5ajCaOgdzj/oW+0eQV9WxKBDZw5+ycmKmeaTXjInS/W0BzpGLo2xR2aBwZdg==
 
-undici@^5.14.0:
+undici@^5.14.0, undici@^5.4.0:
   version "5.21.2"
   resolved "https://registry.yarnpkg.com/undici/-/undici-5.21.2.tgz#329f628aaea3f1539a28b9325dccc72097d29acd"
   integrity sha512-f6pTQ9RF4DQtwoWSaC42P/NKlUjvezVvd9r155ohqkwFNRyBKM3f3pcty3ouusefNRyM25XhIQEbeQ46sZDJfQ==
   dependencies:
     busboy "^1.6.0"
 
-undici@^5.4.0:
-  version "5.14.0"
-  resolved "https://registry.yarnpkg.com/undici/-/undici-5.14.0.tgz#1169d0cdee06a4ffdd30810f6228d57998884d00"
-  integrity sha512-yJlHYw6yXPPsuOH0x2Ib1Km61vu4hLiRRQoafs+WUgX1vO64vgnxiCEN9dpIrhZyHFsai3F0AEj4P9zy19enEQ==
-  dependencies:
-    busboy "^1.6.0"
-
 union-value@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/union-value/-/union-value-1.0.1.tgz#0b6fe7b835aecda61c6ea4d4f02c14221e109847"