diff --git a/.husky/pre-commit b/.husky/pre-commit
index d0a7784..6064714 100644
--- a/.husky/pre-commit
+++ b/.husky/pre-commit
@@ -1 +1 @@
-npx lint-staged
\ No newline at end of file
+npx lint-staged && node --test ./tests/
\ No newline at end of file
diff --git a/src/commands/handler.ts b/src/commands/handler.ts
index a649f41..b9833e7 100644
--- a/src/commands/handler.ts
+++ b/src/commands/handler.ts
@@ -484,11 +484,11 @@ export class CommandHandler extends BaseHandler {
 			option.onPermissionsFail?.bind(option) ??
 			commandInstance.onPermissionsFail?.bind(commandInstance) ??
 			this.client.options.commands?.defaults?.onPermissionsFail;
-		option.botPermissions = PermissionsBitField.add(
+		option.botPermissions = new PermissionsBitField().add(
 			option.botPermissions ?? PermissionsBitField.None,
 			commandInstance.botPermissions,
 		);
-		option.defaultMemberPermissions ??= PermissionsBitField.add(
+		option.defaultMemberPermissions ??= new PermissionsBitField().add(
 			option.defaultMemberPermissions ?? PermissionsBitField.None,
 			commandInstance.defaultMemberPermissions,
 		);
diff --git a/src/structures/extra/BitField.ts b/src/structures/extra/BitField.ts
index 4ad5706..15de184 100644
--- a/src/structures/extra/BitField.ts
+++ b/src/structures/extra/BitField.ts
@@ -18,21 +18,6 @@ export class BitField<T extends object> {
 		return this.bit;
 	}
 
-	add(...bits: (BitFieldResolvable<T> | undefined)[]): bigint {
-		for (const bit of bits) {
-			if (!bit) continue;
-			this.bit |= this.resolve(bit);
-		}
-		return this.bit;
-	}
-
-	remove(...bits: BitFieldResolvable<T>[]): bigint {
-		for (const bit of bits) {
-			this.bit &= ~this.resolve(bit);
-		}
-		return this.bit;
-	}
-
 	has(...bits: BitFieldResolvable<T>[]) {
 		const bitsResolved = bits.map(bit => this.resolve(bit));
 		return bitsResolved.every(bit => (this.bits & bit) === bit);
@@ -47,10 +32,6 @@ export class BitField<T extends object> {
 		return this.bits === this.resolve(other);
 	}
 
-	resolve(bits: BitFieldResolvable<T>): bigint {
-		return BitField.resolve<T>(bits);
-	}
-
 	keys(bits: BitFieldResolvable<T>[] = [this.bits]) {
 		const bitsResolved = bits.map(bit => this.resolve(bit));
 		return Object.entries(this.Flags).reduce((acc, value) => {
@@ -73,27 +54,25 @@ export class BitField<T extends object> {
 		}, [] as bigint[]);
 	}
 
-	static add<T extends object>(base: BitFieldResolvable<T>, ...bits: (BitFieldResolvable<T> | undefined)[]) {
-		base = BitField.resolve(base);
-
+	add(...bits: (BitFieldResolvable<T> | undefined)[]) {
 		for (const bit of bits) {
 			if (!bit) continue;
-			base |= BitField.resolve(bit);
+			this.bits |= this.resolve(bit);
 		}
-		return base;
+		return this.bits;
 	}
 
-	static remove<T extends object>(base: BitFieldResolvable<T>, ...bits: BitFieldResolvable<T>[]): bigint {
-		base = BitField.resolve(base);
-
+	remove(...bits: BitFieldResolvable<T>[]): bigint {
 		for (const bit of bits) {
-			base &= ~BitField.resolve(bit);
+			this.bits &= ~this.resolve(bit);
 		}
-		return base;
+		return this.bits;
 	}
 
-	static resolve<T extends object>(bits: BitFieldResolvable<T>): bigint {
+	resolve(bits: BitFieldResolvable<T>): bigint {
 		switch (typeof bits) {
+			case 'string':
+				return this.resolve(this.Flags[bits]);
 			case 'number':
 				return BigInt(bits);
 			case 'bigint':
@@ -102,10 +81,12 @@ export class BitField<T extends object> {
 				if (!Array.isArray(bits)) {
 					throw new TypeError(`Cannot resolve permission: ${bits}`);
 				}
-				return bits.map(x => BitField.resolve(x)).reduce((acc, cur) => acc | cur, BitField.None);
+				return bits.map(x => this.resolve(x)).reduce((acc, cur) => acc | cur, BitField.None);
 			}
 			default:
-				throw new TypeError(`Cannot resolve permission: ${typeof bits === 'symbol' ? String(bits) : (bits as any)}`);
+				throw new TypeError(
+					`Cannot resolve permission: ${typeof bits === 'symbol' ? String(bits) : (bits as unknown)}`,
+				);
 		}
 	}
 }
diff --git a/src/structures/extra/Permissions.ts b/src/structures/extra/Permissions.ts
index 03173ac..09519b8 100644
--- a/src/structures/extra/Permissions.ts
+++ b/src/structures/extra/Permissions.ts
@@ -8,7 +8,7 @@ export class PermissionsBitField extends BitField<typeof PermissionFlagsBits> {
 
 	constructor(bitfields?: BitFieldResolvable<typeof PermissionFlagsBits>) {
 		super();
-		if (bitfields) this.bit = PermissionsBitField.resolve(bitfields);
+		if (bitfields) this.bit = this.resolve(bitfields);
 	}
 
 	declare keys: (bits?: BitFieldResolvable<typeof PermissionFlagsBits>[]) => PermissionStrings;
@@ -21,12 +21,26 @@ export class PermissionsBitField extends BitField<typeof PermissionFlagsBits> {
 		return super.has(...bits);
 	}
 
-	static resolve<T extends object = typeof PermissionFlagsBits>(bits: BitFieldResolvable<T>): bigint {
+	resolve<T extends typeof PermissionFlagsBits>(bits: BitFieldResolvable<T>): bigint {
+		return PermissionsBitField.resolve(bits);
+	}
+
+	static resolve<T extends typeof PermissionFlagsBits>(bits: BitFieldResolvable<T>): bigint {
 		switch (typeof bits) {
 			case 'string':
 				return PermissionsBitField.resolve(PermissionFlagsBits[bits as keyof typeof PermissionFlagsBits]);
+			case 'number':
+				return BigInt(bits);
+			case 'bigint':
+				return bits;
+			case 'object': {
+				if (!Array.isArray(bits)) {
+					throw new TypeError(`Cannot resolve permission: ${bits}`);
+				}
+				return bits.map(x => PermissionsBitField.resolve(x)).reduce((acc, cur) => acc | cur, BitField.None);
+			}
 			default:
-				return BitField.resolve(bits);
+				throw new TypeError(`Cannot resolve permission: ${typeof bits === 'symbol' ? String(bits) : (bits as any)}`);
 		}
 	}
 }
diff --git a/tests/bitfield.test.js b/tests/bitfield.test.js
new file mode 100644
index 0000000..9898525
--- /dev/null
+++ b/tests/bitfield.test.js
@@ -0,0 +1,67 @@
+//@ts-check
+const { describe, test } = require('node:test');
+const { PermissionsBitField } = require('../lib/structures/extra/Permissions');
+const assert = require('node:assert/strict');
+const { PermissionFlagsBits } = require('../lib/types');
+const { BitField } = require('../lib/structures/extra/BitField');
+
+describe('PermissionsBitField', () => {
+	test('constructor', () => {
+		const p = new PermissionsBitField(['CreateEvents']);
+		assert.equal(p.bits, PermissionFlagsBits.CreateEvents);
+	});
+
+	test('add', () => {
+		const p = new PermissionsBitField(['CreateEvents']);
+		p.add(['AttachFiles']);
+		p.add('ChangeNickname');
+		assert.equal(
+			p.bits,
+			PermissionFlagsBits.CreateEvents | PermissionFlagsBits.AttachFiles | PermissionFlagsBits.ChangeNickname,
+		);
+	});
+
+	test('remove', () => {
+		const p = new PermissionsBitField(['CreateEvents']);
+		p.remove('CreateEvents');
+		assert.equal(p.bits, BitField.None);
+	});
+
+	test('keys', () => {
+		const p = new PermissionsBitField(['CreateEvents', 'Administrator']);
+		p.add(['AttachFiles']);
+		p.add('ChangeNickname');
+
+		const keys = ['CreateEvents', 'Administrator', 'AttachFiles', 'ChangeNickname'];
+		assert.equal(
+			true,
+			p.keys().every(x => keys.includes(x)),
+		);
+		assert.equal(p.keys().length, 4);
+	});
+
+	test('values', () => {
+		const p = new PermissionsBitField(['CreateEvents']);
+		p.add('Administrator');
+		p.add(['ChangeNickname']);
+		assert.deepEqual(p.values(), [
+			PermissionFlagsBits.Administrator,
+			PermissionFlagsBits.ChangeNickname,
+			PermissionFlagsBits.CreateEvents,
+		]);
+	});
+
+	test('missings', () => {
+		const p = new PermissionsBitField(['CreateEvents']);
+		p.add('Administrator');
+		p.add(['ChangeNickname']);
+		assert.deepEqual(p.missings('Connect'), [PermissionFlagsBits.Connect]);
+	});
+
+	test('equals', () => {
+		const p = new PermissionsBitField(['CreateEvents']);
+		p.add(['ChangeNickname']);
+		assert.deepEqual(p.equals(['ChangeNickname', 'CreateEvents']), true);
+		assert.deepEqual(p.equals('Connect'), false);
+	});
+});