diff --git a/src/base/admin.ts b/src/base/admin.ts
index 94e6b47..c1b5ed1 100644
--- a/src/base/admin.ts
+++ b/src/base/admin.ts
@@ -7,7 +7,7 @@ import type {
   UpdateWhitelistInput,
   OpitonalArray,
 } from '../contracts/types';
-import {Base} from './base';
+import type {Base} from './base';
 
 export class Admin<M extends ContractMode = ContractMode> {
   constructor(private readonly base: Base<M>) {}
diff --git a/src/base/base.ts b/src/base/base.ts
index 582079f..adb5455 100644
--- a/src/base/base.ts
+++ b/src/base/base.ts
@@ -1,4 +1,4 @@
-import {Warp, Contract, ArWallet, CustomSignature} from 'warp-contracts';
+import {Warp, Contract, ArWallet, type CustomSignature} from 'warp-contracts';
 import {SnarkjsExtension} from 'warp-contracts-plugin-snarkjs';
 import {EthersExtension} from 'warp-contracts-plugin-ethers';
 import type {ContractInputGeneric, ContractMode, ContractState} from '../contracts/types/contract';
diff --git a/src/bin/evolve.ts b/src/bin/evolve.ts
index c00e85f..2b718bd 100644
--- a/src/bin/evolve.ts
+++ b/src/bin/evolve.ts
@@ -1,4 +1,4 @@
-import {JWKInterface, Warp} from 'warp-contracts';
+import type {JWKInterface, Warp} from 'warp-contracts';
 import {ArweaveSigner} from 'warp-contracts-plugin-deploy';
 
 /** Evolve an existing contract with a new source code. */
diff --git a/src/bin/utils.ts b/src/bin/utils.ts
index cd2bf27..6d4e01e 100644
--- a/src/bin/utils.ts
+++ b/src/bin/utils.ts
@@ -1,5 +1,6 @@
 import {readFileSync} from 'fs';
-import {JWKInterface, Warp, WarpFactory} from 'warp-contracts';
+import type {JWKInterface, Warp} from 'warp-contracts';
+import {WarpFactory} from 'warp-contracts';
 import {DeployPlugin} from 'warp-contracts-plugin-deploy';
 import {prepareState as prepareStateWithWarp} from './deploy';
 import {ContractState} from '../contracts/types';
diff --git a/tests/README.md b/tests/README.md
index 4127613..f6eb0bc 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -8,3 +8,4 @@ The tests are as follows:
 - `crud` tests for basic CRUD functionality, such as checking for existing keys, not removing an already removed key and such.
 - `htx` tests use a custom contract where assume Bundlr usage and instead of values themselves, we store `valueHash.txid` as values.
 - `multi` tests using a single Warp instance with multiple contracts, and multiple HollowDB instances.
+- `null` tests null values, which are not allowed due to ambiguity between a null value and non-existent value.
diff --git a/tests/hooks/index.ts b/tests/hooks/index.ts
index 5767999..39efff9 100644
--- a/tests/hooks/index.ts
+++ b/tests/hooks/index.ts
@@ -3,7 +3,7 @@ import {LoggerFactory, Warp, WarpFactory} from 'warp-contracts';
 import {DeployPlugin} from 'warp-contracts-plugin-deploy';
 import {Redis} from 'ioredis';
 import {overrideCache} from '../utils/cache';
-import {Wallet} from 'warp-contracts/lib/types/contract/testing/Testing';
+import type {Wallet} from 'warp-contracts/lib/types/contract/testing/Testing';
 
 /**
  * Setup Warp instance for a test, connected to Arlocal at the provided port.
diff --git a/tests/utils/index.ts b/tests/utils/index.ts
index f8ca64a..880ce85 100644
--- a/tests/utils/index.ts
+++ b/tests/utils/index.ts
@@ -1,8 +1,8 @@
+import type {Warp, JWKInterface} from 'warp-contracts';
 import {randomBytes} from 'crypto';
-import {Warp, JWKInterface} from 'warp-contracts';
 import {readFileSync} from 'fs';
-import {deploy} from '../../src/bin/deploy';
 import {computeKey} from 'hollowdb-prover';
+import {deploy} from '../../src/bin/deploy';
 import {ContractState} from '../../src/contracts/types';
 
 /** Add funds to any wallet. */