diff --git a/src/lib/command/middleware/Middleware.ts b/src/lib/command/middleware/Middleware.ts
index 9c148a44..bdb46202 100644
--- a/src/lib/command/middleware/Middleware.ts
+++ b/src/lib/command/middleware/Middleware.ts
@@ -18,7 +18,7 @@ export class Middleware
 	 * any invalid input.<br><br>
 	 *
 	 * Valid types are:<br>
-	 * <pre class="prettyprint"><code>'String' | 'Number' | 'User' | 'Member' | 'BannedUser' | 'Role' | 'Channel'</code></pre><br>
+	 * <pre class="prettyprint"><code>'String' | 'Number' | 'Duration' | 'User' | 'Member' | 'BannedUser' | 'Role' | 'Channel'</code></pre><br>
 	 *
 	 * Example:<br>
 	 * <pre class="prettyprint"><code>{ 'mem': 'Member', 'age>': 'Number', '...desc': 'String' }
@@ -52,7 +52,7 @@ export class Middleware
 	 * </code></pre><br>
 	 *
 	 * If verifying a `BannedUser` returned from the ResolveArgs middleware,
-	 * use the `User` type.
+	 * use the `User` type. If verifying `Duration` type, `Number` should be used.
 	 *
 	 * This middleware does not modify args in any way.
 	 * @name expect
diff --git a/src/lib/command/middleware/ResolveArgs.ts b/src/lib/command/middleware/ResolveArgs.ts
index 88bf6da6..5eb8493f 100644
--- a/src/lib/command/middleware/ResolveArgs.ts
+++ b/src/lib/command/middleware/ResolveArgs.ts
@@ -48,6 +48,25 @@ export function resolveArgs<T extends Bot, U extends Command<T>>(argTypes: { [na
 					`in arg \`${name}\`: \`${arg}\` could not be resolved to a number.\n${usage}`);
 			}
 
+			else if (type === 'Duration')
+			{
+				let duration: number, match: RegExpMatchArray;
+				if (/^(?:\d+(?:\.\d+)?)[s|m|h|d]$/.test(arg))
+				{
+					match = arg.match(/(\d+(?:\.\d+)?)(s|m|h|d)$/);
+					duration = parseFloat(match[1]);
+					duration = match[2] === 's'
+						? duration * 1000 : match[2] === 'm'
+						? duration * 1000 * 60 : match[2] === 'h'
+						? duration * 1000 * 60 * 60 : match[2] === 'd'
+						? duration * 1000 * 60 * 60 * 24 : null;
+				}
+				if (!duration) throw new Error(
+					`in arg \`${name}\`: \`${arg}\` could not be resolved to a duration.\n${usage}`);
+
+				args[index] = duration;
+			}
+
 			else if (type === 'User')
 			{
 				let user: User;
diff --git a/src/lib/types/ResolveArgType.ts b/src/lib/types/ResolveArgType.ts
index 215bd644..be7adfac 100644
--- a/src/lib/types/ResolveArgType.ts
+++ b/src/lib/types/ResolveArgType.ts
@@ -1,7 +1,7 @@
-export type ResolveArgType = 'String' | 'Number' | 'User' | 'Member' | 'BannedUser' | 'Channel' | 'Role';
+export type ResolveArgType = 'String' | 'Number' | 'Duration' | 'User' | 'Member' | 'BannedUser' | 'Channel' | 'Role';
 
 /**
  * @typedef {string} ResolveArgType Valid arg type values for the ResolveArgs middleware
  * Can be one of the following string literals:<br>
- * <pre class="prettyprint"><code>'String' | 'Number' | 'User' | 'Member' | 'BannedUser' | 'Role' | 'Channel'</code></pre>
+ * <pre class="prettyprint"><code>'String' | 'Number' | 'Duration' | 'User' | 'Member' | 'BannedUser' | 'Role' | 'Channel'</code></pre>
  */