diff --git a/src/client.js b/src/client.js
index 0d162369..d821d8f2 100644
--- a/src/client.js
+++ b/src/client.js
@@ -60,8 +60,9 @@ export class Client {
 	 * @param {ClientOptions} [options] An object providing values to initialize this instance.
 	 */
 	constructor(apiKey, blog, options = {}) {
+		const baseUrl = options.baseUrl ?? "https://rest.akismet.com";
 		this.apiKey = apiKey;
-		this.baseUrl = new URL(options.baseUrl ?? "https://rest.akismet.com/");
+		this.baseUrl = new URL(baseUrl.slice(-1) == "/" ? baseUrl : `${baseUrl}/`);
 		this.blog = blog;
 		this.isTest = options.isTest ?? false;
 		this.userAgent = options.userAgent ?? `Node.js/${version.slice(1)} | Akismet/${Client.#version}`;