diff --git a/src/commands/decorators.ts b/src/commands/decorators.ts
index cfdbf83..adf701b 100644
--- a/src/commands/decorators.ts
+++ b/src/commands/decorators.ts
@@ -1,11 +1,11 @@
 import type { FlatObjectKeys, PermissionStrings } from '../common';
+import { PermissionsBitField } from '../structures/extra/Permissions';
 import {
 	ApplicationCommandType,
 	ApplicationIntegrationType,
 	type EntryPointCommandHandlerType,
 	InteractionContextType,
 	type LocaleString,
-	PermissionFlagsBits,
 } from '../types';
 import type { CommandOption, OptionsRecord, SubCommand } from './applications/chat';
 import type { DefaultLocale, ExtraProps, IgnoreCommand, MiddlewareContext } from './applications/shared';
@@ -159,11 +159,11 @@ export function Declare(declare: CommandDeclareOptions) {
 			integrationTypes = declare.integrationTypes?.map(i => ApplicationIntegrationType[i]) ?? [
 				ApplicationIntegrationType.GuildInstall,
 			];
-			defaultMemberPermissions = Array.isArray(declare.defaultMemberPermissions)
-				? declare.defaultMemberPermissions?.reduce((acc, prev) => acc | PermissionFlagsBits[prev], BigInt(0))
+			defaultMemberPermissions = declare.defaultMemberPermissions
+				? PermissionsBitField.resolve(declare.defaultMemberPermissions)
 				: declare.defaultMemberPermissions;
-			botPermissions = Array.isArray(declare.botPermissions)
-				? declare.botPermissions?.reduce((acc, prev) => acc | PermissionFlagsBits[prev], BigInt(0))
+			botPermissions = declare.botPermissions
+				? PermissionsBitField.resolve(declare.botPermissions)
 				: declare.botPermissions;
 			description = '';
 			type: ApplicationCommandType = ApplicationCommandType.ChatInput;
diff --git a/src/commands/handle.ts b/src/commands/handle.ts
index 721b93f..8558b7d 100644
--- a/src/commands/handle.ts
+++ b/src/commands/handle.ts
@@ -169,10 +169,18 @@ export class HandleCommand {
 		resolver: OptionResolverStructure,
 		context: CommandContext,
 	) {
-		if (context.guildId && command.botPermissions && interaction.appPermissions) {
-			const permissions = this.checkPermissions(interaction.appPermissions, command.botPermissions);
-			if (permissions) return command.onBotPermissionsFail?.(context, permissions);
+		if (context.guildId && interaction.appPermissions) {
+			if (command.botPermissions) {
+				const permissions = this.checkPermissions(interaction.appPermissions, command.botPermissions);
+				if (permissions) return command.onBotPermissionsFail?.(context, permissions);
+			}
+
+			if (command.defaultMemberPermissions) {
+				const permissions = this.checkPermissions(interaction.member!.permissions, command.defaultMemberPermissions);
+				if (permissions) return command.onPermissionsFail?.(context, permissions);
+			}
 		}
+
 		if (!(await this.runOptions(command, context, resolver))) return;
 
 		const resultGlobal = await this.runGlobalMiddlewares(command, context);
diff --git a/src/commands/handler.ts b/src/commands/handler.ts
index ce58017..a649f41 100644
--- a/src/commands/handler.ts
+++ b/src/commands/handler.ts
@@ -3,6 +3,7 @@ import { basename, dirname } from 'node:path';
 import type { EntryPointCommand } from '.';
 import type { Logger, MakeRequired, NulleableCoalising, OmitInsert } from '../common';
 import { BaseHandler, isCloudfareWorker } from '../common';
+import { PermissionsBitField } from '../structures/extra/Permissions';
 import {
 	type APIApplicationCommandChannelOption,
 	type APIApplicationCommandIntegerOption,
@@ -483,8 +484,14 @@ export class CommandHandler extends BaseHandler {
 			option.onPermissionsFail?.bind(option) ??
 			commandInstance.onPermissionsFail?.bind(commandInstance) ??
 			this.client.options.commands?.defaults?.onPermissionsFail;
-		option.botPermissions ??= commandInstance.botPermissions;
-		option.defaultMemberPermissions ??= commandInstance.defaultMemberPermissions;
+		option.botPermissions = PermissionsBitField.add(
+			option.botPermissions ?? PermissionsBitField.None,
+			commandInstance.botPermissions,
+		);
+		option.defaultMemberPermissions ??= PermissionsBitField.add(
+			option.defaultMemberPermissions ?? PermissionsBitField.None,
+			commandInstance.defaultMemberPermissions,
+		);
 		option.contexts ??= commandInstance.contexts;
 		option.integrationTypes ??= commandInstance.integrationTypes;
 		option.props ??= commandInstance.props;
diff --git a/src/structures/extra/BitField.ts b/src/structures/extra/BitField.ts
index 8606003..745fd9b 100644
--- a/src/structures/extra/BitField.ts
+++ b/src/structures/extra/BitField.ts
@@ -18,24 +18,19 @@ export class BitField<T extends object> {
 		return this.bit;
 	}
 
-	add(...bits: BitFieldResolvable<T>[]): bigint {
-		let reduced = BitField.None;
-
+	add(...bits: (BitFieldResolvable<T> | undefined)[]): bigint {
 		for (const bit of bits) {
-			reduced |= this.resolve(bit);
+			if (!bit) continue;
+			this.bit |= this.resolve(bit);
 		}
-
-		return (this.bit |= reduced);
+		return this.bit;
 	}
 
 	remove(...bits: BitFieldResolvable<T>[]): bigint {
-		let reduced = BitField.None;
-
 		for (const bit of bits) {
-			reduced |= this.resolve(bit);
+			this.bit &= ~this.resolve(bit);
 		}
-
-		return (this.bit &= ~reduced);
+		return this.bit;
 	}
 
 	has(...bits: BitFieldResolvable<T>[]) {
@@ -52,27 +47,17 @@ export class BitField<T extends object> {
 		return this.bits === this.resolve(other);
 	}
 
-	resolve(bits?: BitFieldResolvable<T>): bigint {
+	resolve(bits: BitFieldResolvable<T>): bigint {
 		switch (typeof bits) {
-			case 'number':
-				return BigInt(bits);
 			case 'string':
-				return this.resolve(this.Flags[bits]);
-			case 'bigint':
-				return bits;
-			case 'object': {
-				if (!Array.isArray(bits)) {
-					throw new TypeError(`Cannot resolve permission: ${bits}`);
-				}
-				return bits.map(x => this.resolve(x)).reduce((acc, cur) => acc | cur, BitField.None);
-			}
+				return BitField.resolve(this.Flags[bits]);
 			default:
-				throw new TypeError(`Cannot resolve permission: ${typeof bits === 'symbol' ? String(bits) : (bits as any)}`);
+				return BitField.resolve<T>(bits);
 		}
 	}
 
 	keys(bits: BitFieldResolvable<T>[] = [this.bits]) {
-		const bitsResolved = bits.map(bit => BigInt(this.resolve(bit)));
+		const bitsResolved = bits.map(bit => this.resolve(bit));
 		return Object.entries(this.Flags).reduce((acc, value) => {
 			if (bitsResolved.some(bit => (bit & value[1]) === value[1])) {
 				acc.push(value[0]);
@@ -83,7 +68,7 @@ export class BitField<T extends object> {
 	}
 
 	values(bits: BitFieldResolvable<T>[] = [this.bits]) {
-		const bitsResolved = bits.map(bit => BigInt(this.resolve(bit)));
+		const bitsResolved = bits.map(bit => this.resolve(bit));
 		return Object.entries(this.Flags).reduce((acc, value) => {
 			if (bitsResolved.some(bit => (bit & value[1]) === value[1])) {
 				acc.push(value[1]);
@@ -92,4 +77,40 @@ export class BitField<T extends object> {
 			return acc;
 		}, [] as bigint[]);
 	}
+
+	static add<T extends object>(base: BitFieldResolvable<T>, ...bits: (BitFieldResolvable<T> | undefined)[]) {
+		base = BitField.resolve(base);
+
+		for (const bit of bits) {
+			if (!bit) continue;
+			base |= BitField.resolve(bit);
+		}
+		return base;
+	}
+
+	static remove<T extends object>(base: BitFieldResolvable<T>, ...bits: BitFieldResolvable<T>[]): bigint {
+		base = BitField.resolve(base);
+
+		for (const bit of bits) {
+			base &= ~BitField.resolve(bit);
+		}
+		return base;
+	}
+
+	static resolve<T extends object>(bits: BitFieldResolvable<T>): bigint {
+		switch (typeof bits) {
+			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 => BitField.resolve(x)).reduce((acc, cur) => acc | cur, BitField.None);
+			}
+			default:
+				throw new TypeError(`Cannot resolve permission: ${typeof bits === 'symbol' ? String(bits) : (bits as any)}`);
+		}
+	}
 }
diff --git a/src/structures/extra/Permissions.ts b/src/structures/extra/Permissions.ts
index 87c27a2..e13155c 100644
--- a/src/structures/extra/Permissions.ts
+++ b/src/structures/extra/Permissions.ts
@@ -20,4 +20,13 @@ export class PermissionsBitField extends BitField<typeof PermissionFlagsBits> {
 	strictHas(...bits: BitFieldResolvable<typeof PermissionFlagsBits>[]) {
 		return super.has(...bits);
 	}
+
+	static resolve<T extends object = typeof PermissionFlagsBits>(bits: BitFieldResolvable<T>): bigint {
+		switch (typeof bits) {
+			case 'string':
+				return PermissionsBitField.resolve(PermissionFlagsBits[bits as keyof typeof PermissionFlagsBits]);
+			default:
+				return BitField.resolve(bits);
+		}
+	}
 }